Document:

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                                                              Exhibit 10(c)(iii)

                        [LETTERHEAD OF HALE AND DORR LLP]

                                           November 5, 1999

VIA FEDERAL EXPRESS

Jeffrey A. Bernfeld, Esq.
American Science and Engineering, Inc.
829 Middlesex Turnpike
Billerica, MA 01821

      Re:   Standard Form Lease dated October 29, 1999 between ACP Manning
            Associates, LLC, as Lessor, and American Science and Engineering,
            Inc., as Lessee, with respect to Premises located at 33 Manning Rd.,
            Billerica, MA

Dear Jeff:

      In conjunction with your letter to me dated November 5, 1999 authorizing
me to release the above-referenced Lease from escrow, enclosed please find two
(2) fully executed originals of the same. Please note that under cover of this
letter I am simultaneously forwarding to our client a fully executed original of
the Lease along with the Security Deposit.

      Should you have any questions, please do not hesitate to contact me. It
was a pleasure working with you.

                                           Very truly yours

                                           /s/ Jonathan C. Black

                                           Jonathan C. Black
JCB/lmt

cc:   Mr. Roger Altreuter (w/enc.)
      William R. O'Reilly, Jr., Esq. (w/o enc.)
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                               STANDARD FORM LEASE

                    33 MANNING ROAD, BILLERICA, MASSACHUSETTS

      LEASE made this 29th day of October, 1999, by and between ACP Manning
Associates, LLC, a Massachusetts limited liability company ("Lessor") and
American Science and Engineering, Inc., a Massachusetts corporation ("Lessee").

                              W I T N E S S E T H:

                                    ARTICLE I

                         Premises; Certain Defined Terms

      Section 1. In consideration of the rents and covenants herein contained on
the part of the Lessee to be paid, performed and observed, the Lessor hereby
leases to the Lessee and the Lessee hereby leases from the Lessor, subject to
the terms and provisions hereinafter set forth, certain premises (hereinafter
called the "demised premises," or the "Premises") consisting of 56,250 square
feet of floor area in the building (the "Building") situated at 33 Manning Road,
Billerica, Massachusetts and the land described in Exhibit A attached hereto
(the "Land"), a copy of a plan of the Building being attached hereto as Exhibit
B; together with the exclusive right to use the parking areas on the Land as the
same may exist from time to time, for parking purposes and for product testing
and display of products to Lessee's customers in the ordinary course of its
business only, and the driveways and walkways on the Land, as the same may exist
from time to time, for roadway and walkway purposes only.

      Section 2. The demised premises are leased subject to the reservation to
the Lessor of the roof and exterior walls of the demised premises and of the
Building and subject to the Lessor's reservation of the right (without thereby
assuming the obligation) to install, maintain, use, repair and replace (in such
manner as to reduce to a minimum to the extent reasonably practicable the
interference with Lessee's use of the demised premises) all pipes, ducts, wires,
meters, utility lines and the like which are, in the judgment of the Lessor,
required to be in the demised premises. The Lessor reserves the right to alter,
increase and relocate such parking areas, driveways and walkways (so long as the
same does not materially impair Lessee's rights under this Lease) and any common
facilities within the Building.

      Section 3. For the purposes of this Lease, the following capitalized terms
shall have the meanings given to them below:

Broker: CB Richard Ellis-NE Partners and Nordblom Company

Lessee's Notice Address: 829 Middlesex Turnpike, Billerica, MA 01821
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Lessee's Pro Rata Share: 100% (i.e., the Leasable Square Footage of the Premises
of 56,250 s.f. divided by the Leasable Square Footage of the Building of 56,250
s.f.)

Permitted Use: Light manufacturing and business offices.

Security Deposit Amount: $26,953.13.

                                   ARTICLE II

                              Term and Commencement

      Section 1. TO HAVE AND TO HOLD the demised premises for the original term
of five (5) years and one (1) month from the Commencement Date (the "Term")
unless sooner terminated as herein provided. The "Commencement Date" shall be
December 1, 1999, provided that the obligation of Lessee to pay (ii) Annual Base
Rent (as defined Article III, Section 1) and (ii) Lessee's Pro Rata Share of any
and all real estate taxes and betterments and other assessments (ordinary and
extraordinary), water rents, sewer and other charges which shall be imposed,
assessed or levied upon the Building and the Land in accordance with Article
III, Section 2 hereof shall commence on January 1, 2000. The obligation of
Lessee to pay all other amounts, items and additional rent imposed upon Lessee
pursuant to the terms of this Lease, including, without limitation, the amounts,
items and additional rent set forth in Article III, Sections 4, 5, 6 and 7 and
Article VII of this Lease, shall commence on the Commencement Date.

                                   ARTICLE III

                                      Rent

      Section 1. YIELDING AND PAYING an annual base rent during the Term in the
amount of THREE HUNDRED TWENTY-THREE THOUSAND FOUR HUNDRED THIRTY-SEVEN AND
50/100 DOLLARS ($323,437.50) per year ("Annual Base Rent"), payable in equal
monthly installments of TWENTY-SIX THOUSAND NINE HUNDRED FIFTY-THREE AND 13/100
DOLLARS ($26,953.13). All such rent shall be payable in advance on the first day
of each calendar month during the Term. If the Commencement Date is other than
the first day of a calendar month, Annual Base Rent for the first incomplete
month, prorated at the rate set forth above, shall be paid on the Commencement
Date.

      Section 2. The Lessee shall pay, as additional rent hereunder, Lessee's
Pro Rata Share (as defined in Articles I and XX hereof) of any and all real
estate taxes and betterments and other assessments (ordinary and extraordinary),
water rents, sewer and other charges which shall be imposed, assessed or levied
upon the Building and

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the Land. In addition, the Lessee shall pay 100% of real estate taxes,
betterments and other assessments due to any alterations or improvements made by
the Lessee to the demised premises. The Lessee shall pay such additional rent to
the Lessor upon presentation of the applicable tax bills, together with
computations showing Lessee's Pro Rata Share thereof, but in any event not later
than twenty (20) days prior to the last day or dates on which said taxes may be
paid without interest or penalty, or, at Lessor's request, in monthly
installments in such amounts as Lessor may reasonably require from time to time
which installments shall be due and payable on the same dates as the monthly
installments of annual base rent payable hereunder, with a final adjustment to
be made as soon as all bills are available for the applicable period.

      If this lease shall commence on a date other than the first day of a tax
year or terminate on a date other than the last day of a tax year, the Lessee
for that tax year shall pay to the Lessor only such portion of such additional
rent for the whole tax year as shall be proportionate to the portion of the tax
year contained within the term of this Lease.

      Section 3. The term "real estate taxes" shall mean all taxes and special
assessments of every kind and nature assessed by a governmental authority on the
Land or the Building which the Lessor shall become obligated to pay because of
or in connection with the ownership, leasing and operation of the Land or
Building. The foregoing provisions are predicated upon the present system of
taxation in the Commonwealth of Massachusetts. If taxes upon rentals or
otherwise pertaining to the demised premises shall be substituted, in whole or
in part, for the present ad valorem real estate taxes or assessed in addition
thereto, then Lessee's obligation to pay such taxes shall be based upon such
substituted taxes, to the extent to which the same shall be a substitute for
present ad valorem real estate taxes, together with such additional taxes, and
such substitute or additional taxes shall be deemed to be included within the
term "real estate taxes". Except as hereinabove provided, nothing herein
contained shall otherwise require or be construed to require Lessee to reimburse
Lessor for any inheritance, estate, succession, transfer, gift, franchise,
income or earnings profit, excess profit tax, capital stock, capital levy or
corporate or other similar tax which is or may be imposed upon Lessor or upon
Lessor's business.

      Section 4. Lessee shall pay to Lessor, as additional rent, Lessee's Pro
Rata Share of the costs paid or incurred by Lessor in maintaining and repairing
the Building and any additions to the Building (except only for structural
repairs set forth in Article VI, Section 2), in maintaining and repairing the
Land, including without limitation, parking areas, driveways, walkways and
landscaping thereon. Such costs shall be paid within ten (10) days after receipt
of invoices from Lessor therefor, or at Lessor's election, in accordance with
Section 5 hereof. Such costs shall include, without limitation, (1) all costs of
providing utilities (including without limitation where applicable heat, cooling
and light) for and maintaining and repairing the common areas of the Building,
the parking areas, driveways and walkways on the Land (including,

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without limitation, resurfacing, striping and sweeping) and removing snow and
ice from the parking areas, driveways and walkways on the Land and from the roof
of the Building, (2) all costs of maintaining and repairing all drainage, sewage
and/or septic system and utility facilities and equipment on the Land whether
above or underground, (3) all costs of maintaining the grass and shrubs and
other planted areas and landscaping on the Land, (4) all costs of maintaining
and repairing the Building and any additions thereto (structural repairs set
forth in Article VI, Section 2 excepted), including, without limitation,
maintenance and repair of all fixtures and equipment and utility facilities
serving the demised premises or the Building; and (5) Building management fees
and expenses (which shall not exceed those customarily charged in connection
with single tenant properties and buildings of the same type and character as
the Building and the Land within the locality of the demised premises).

      Section 5. At Lessor's election, Lessee's Pro Rata Share of the costs
referred to in Section 4 of this Article III shall be paid in advance in 12
equal monthly estimated installments (based on an amount estimated by Lessor)
due and payable on the same dates as the monthly installments of annual base
rent payable hereunder. Within ninety days after the end of each fiscal year of
Lessor (meaning the twelve month period used by the Lessor in preparing its
annual financial statements), Lessor shall furnish to Lessee a statement in
reasonable detail setting forth the computation of such costs. Thereupon, Lessee
shall pay any deficiency, and any overpayment shall be credited to Lessee's
obligations hereunder for the then current fiscal year, or, in the case of the
last year of the Term, shall be refunded to Lessee. For purposes of Section 4 of
this Article III if this Lease shall commence on a date other than the first day
of Lessor's fiscal year or terminate on a date other than the last day of
Lessor's fiscal year, the Lessee for that respective fiscal year shall pay to
the Lessor only a proportionate share of Lessor's costs referred to in such
Section 4 for the whole fiscal year as shall be proportionate to the portion of
the fiscal year contained within the Term of this Lease.

      Section 6. Lessee shall pay Lessor, as additional rent hereunder, Lessee's
Pro Rata Share of Lessor's cost of the following insurance on the Building and
the Land: fire and extended coverage insurance and such other insurance covering
all hazards included within customary "all risks" coverage, including without
limitation insurance covering fire, lightning, vandalism, malicious mischief,
and sprinkler leakage, said insurance to be on a full value, repair, or
replacement basis, as determined by Lessor; rent insurance; and such other
insurance as may be requested by Lessor's mortgagee. In addition,
notwithstanding the foregoing, Lessee shall pay as additional rent, 100% of
Lessor's cost of any insurance with respect to the Building or the Land which is
attributable solely to Lessee's particular use of the demised premises.

      Section 7. Lessee shall pay Lessor, as additional rent hereunder, Lessee's
Pro Rata Share of Lessor's cost for comprehensive liability insurance insuring
the Lessor against all claims and demands for any injury to persons or property
which may be claimed to have occurred in or upon the Building or the Land in
such amounts as are

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customarily carried with respect to properties and buildings of the same type
and character as the Building and the Land within the locality of the demised
premises as the same shall be reasonably determined by Lessor from time to time.

      Section 8. All additional rent on account of insurance shall be paid to
Lessor within fifteen (15) days of receipt by Lessee of a bill therefor from
Lessor, which bill shall be accompanied by a copy of the applicable insurance
bills and a computation showing Lessee's Pro Rata Share of the cost thereof, or,
at the election of the Lessor, in advance in twelve (12) equal monthly estimated
installments (based on an amount estimated by Lessor) due and payable on the
same dates as the monthly installments of annual base rent payable hereunder,
with a final adjustment to be made as soon as all applicable bills are available
for such period.

      Section 9. This is, and is intended to be, a NET LEASE, and accordingly
except as expressly otherwise provided for herein, all charges, assessments and
impositions made upon the Land and the Building and all costs, expenses and
other obligations paid or incurred by Lessor of any kind or nature whatsoever in
insuring, maintaining and/or repairing the demised premises or the Building or
the Land or any additions to the Building (other than structural repairs set
forth in Article VI, Section 2 hereof) shall be included in determining Lessor's
costs of which Lessee is obligated to pay a pro rata share or the entirety, as
the case may be, as provided hereinabove.

      Section 10. Any charge, cost, reimbursement, payment or other sum which is
payable by Lessee hereunder to Lessor or any payment required to be paid by
Lessee hereunder to any other party (which payment to said third party is not
paid by Lessee when due) shall constitute additional rent for all purposes under
this Lease.

      Section 11. All payments of base rent and additional rent hereunder shall
be mailed or delivered to the Lessor, when due as set forth herein without
offset or deduction and without previous demand therefore and made payable to
the order of ACP Manning Associates, LLC, c/o CB Richard Ellis-NE Partners, 600
Atlantic Avenue, 22nd Floor, Boston, MA 02210 or otherwise as Lessor may notify
Lessee from time to time.

                                   ARTICLE IV

                                    Covenants

      Lessee covenants and agrees as follows:

      (a) To pay when due the said base rent and additional rent at the times
and in the manner set forth herein.

      (b) To procure any and all licenses and permits required for any use to be
made of the demised premises by Lessee; to keep the demised premises equipped
with

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all safety appliances required by law or ordinance because of any use of the
demised premises by Lessee; and to make any alterations or changes which may be
necessary to meet the obligations and standards promulgated under the
Occupational Safety and Health Act of 1970, as amended, which are related to
Lessee's use and occupation of the demised premises.

      (c) To pay promptly when due the entire cost of any work to the demised
premises undertaken by Lessee so that said premises shall at all times be free
of liens for labor and materials; to procure all necessary permits before
undertaking such work; to do all of such work in a good and workmanlike manner,
employing new materials of good quality and complying with all governmental and
insurance requirements; and to save Lessor harmless and indemnified from all
injury, loss, claims or damage to any person or property occasioned by or
growing out of such work including, without limitation, reasonable attorneys'
fees. If so requested by Lessor, Lessee shall take over Lessor's defense in any
action related to work undertaken by Lessee on the demised premises.

      (d) To permit Lessor and anyone claiming under Lessor at reasonable times
upon twenty-four (24) hours prior notice to enter into and examine the demised
premises and to show the demised premises to prospective purchasers or, during
the last year of the term of this Lease to prospective tenants, provided that
Lessor shall not thereby unreasonably interfere with the conduct of Lessee's
business; to permit Lessor to enter said premises to make such repairs,
improvements, alterations or additions thereto as may be required in order to
comply with the requirements of any public authority having jurisdiction of the
demised premises, or as may be required of Lessor under the terms of this lease,
provided that such entry shall not unreasonably interfere with the conduct of
Lessee's business; and to permit the affixing to any suitable part of the
demised premises a reasonable notice for letting or selling the demised premises
or the Building; to permit Lessor to enter the demised premises at any time to
make emergency repairs.

      (e) To pay when due any and all State, Federal or local taxes based upon
Lessee's use or occupation of the demised premises or pertaining to Lessee's
personal property or resulting from any permitted alteration, additions or
improvements made by Lessee to the demised premises.

      (f) To conform to and comply with all laws, orders, and regulations of any
governmental authorities and any public body or officer having jurisdiction over
the demised premises.

      (g) To comply with any rules, regulations or recommendations of the
National Board of Fire Underwriters, any rating bureau or any similar
association performing such function, and any insurance company insuring the
demised premises with respect to the demised premises and/or Lessee's use and
occupation thereof.

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      (h) To keep the demised premises adequately heated for the protection of
the plumbing therein.

      (i) To permit no waste with respect to the demised premises.

      (j) To permit no storage of materials outside of the demised premises
except for such temporary storage as may be required for reasonable periods of
time due to unforeseen circumstances or emergencies.

      (k) To comply with such reasonable rules and regulations now or hereafter
made by Lessor for and with respect to the care and use of the Building and Land
and their facilities and approaches, it being understood that Lessor shall not
be liable to Lessee for the failure of any other tenants of the Building to
conform to such rules and regulations.

      (l) Not to do, or suffer to be done, or to keep, or suffer to be kept or
omit to do anything in, upon or about the demised premises which may prevent the
obtaining of any insurance on the Building or the demised premises or which may
make void or voidable any insurance on the Building or the demised premises.

                                    ARTICLE V

                             Use of Demised Premises

      Section 1. The Lessee shall have the right to use the demised premises for
the Permitted Uses and for no other purpose whatsoever, but in no event shall
Lessee conduct at the demised premises any use or do anything which constitutes
a nuisance or violates any provisions of any zoning, building or other
applicable laws, ordinances or regulations.

      Section 2. Lessee further agrees as follows:

      (a) Lessee shall always conduct its operations in the demised premises
under its present trade name or any future trade name which is not offensive or
in violation of law, unless Lessor shall otherwise consent in writing, which
consent shall not be unreasonably withheld;

      (b) Lessee shall not permit any auction, fire, going-out-of-business, or
bankruptcy sales or any retail sales whatsoever to be conducted within the
demised premises, without the prior written consent of the Lessor;

      (c) Lessee shall not use the sidewalks, parking areas or other outside
areas for advertising or business purposes (except as expressly provided herein)
or otherwise obstruct the same;

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      (d) Lessee shall, at its own cost and expense, be responsible for the
prompt regular removal of all trash, refuse, and the like, from the demised
premises and shall insure that same be kept in covered containers at all times;

      (e) Intentionally omitted;

      (f) Lessee shall take whatever measures are necessary to insure that floor
load limitations are not exceeded in the demised premises; and

      (g) Lessee shall not cause any offensive odors or loud noise (including,
but without limitation, the use of loudspeakers), nor take nor permit any action
which constitutes a nuisance or menace to any other occupant of other premises
in the Building, and in no event shall any loud noises or offensive odors be
emitted from the demised premises.

                                   ARTICLE VI

                             Repairs and Alterations

      Section 1. The Lessee shall keep the demised premises in a neat, clean,
sanitary condition and in good order and repair and in good working condition,
including all electrical, plumbing, gas, sprinkler, and equipment within or
serving the demised premises (including without limitation the maintenance,
repair and/or replacement of the HVAC system serving the demised premises) and
all fixtures and interior walls, floors, ceilings, signs (including exterior
signs where permitted), and all interior building appliances and similar
equipment and the exterior and the interior portions of all windows, window
frames, doors, door frames, and all other glass or plateglass thereon. In
connection therewith, and without limiting Lessee's obligations hereunder,
Lessee shall perform the maintenance as set forth on the HVAC maintenance
schedule attached hereto as Exhibit C and made a part hereof. Subject to
approval by Lessor of the plans and specifications therefor (which shall not be
unreasonably withheld so long as Lessee complies (and Lessee hereby covenants
and agrees to so comply) in all respects with Article VI, Section 6 of this
Lease, including, without limitation, the requirements set forth in Article VI,
Section 6, Subparagraphs (a), (c) and (d) of this Lease), Lessee shall have the
right to raise the roof in accordance with the plans and specifications so
approved by Lessor. To the extent that Lessee raises the roof (subject to plan
and specification approval by Lessor as set forth herein), then Lessee shall be
responsible (at its sole cost and expense) to maintain in good order and repair
and in good working condition that portion of the roof so raised as well as all
joints and seems connecting the portion of the roof not raised with the portion
of the roof raised by Lessee.

      Section 2. The Lessor shall, at its expense, promptly after receipt of
written notice from the Lessee, make any necessary repairs to the foundations,
roof (except for

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those portions of the roof raised by Lessee (and the joints and seems connected
thereto) in accordance with Article VI, Section 1 hereof), beams, girders,
mullions and exterior walls of the demised premises only (exclusive of glass,
window frames, windows, doors, door frames and signs, which repairs shall be
made by the Lessee) except where such repairs are required by reason of any act
or negligence of the Lessee, its employees, agents, licensees, suppliers,
contractors, or guests ("structural repairs"). The Lessor shall commence repairs
to be made by it as promptly as practicable after the receipt of such notice,
provided, however, that the Lessor (without limiting Section 14 of Article XXII
hereof) shall not be liable for a delay in commencement of the making of such
repairs or for a delay or failure to complete such repairs where such delay or
failure is attributable to strikes or other labor conditions, inability or
difficulty in obtaining materials, services or permits, wars, delays due to the
weather, or other cause beyond the reasonable control of the Lessor.

      Section 3. Lessor shall be responsible for the maintenance of the grass
and shrubs located on the Land and shall be responsible for maintaining,
repairing, lighting and removing snow from the parking areas, driveways and
walkways on the Land, except where the necessity thereof is due to the willful
or negligent acts of Lessee or its agents, employees, licensees, suppliers,
contractors or guests.

      Section 4. All costs paid or incurred by Lessor in performing any of its
obligations under this Article VI (except for structural repairs set forth in
Section 2 hereof) shall be included in Lessor's costs of maintaining and
repairing as set forth in Article III, Section 4.

      Section 5. The Lessee shall at the expiration or earlier termination of
this lease remove its goods and effects and peaceably yield up the demised
premises, clean and in the same order, repair and condition as at the
Commencement Date of the term hereof, or as the same may be put in during the
term hereof, reasonable wear and tear excepted (provided good maintenance
practices are employed), except for repairs which the Lessor agrees to make as
herein provided and except for damage by fire or insured casualty, and Lessee
shall promptly repair any injury done to the demised premises, the Building or
the Land by the installation or removal of the Lessee's fixtures or other
property.

      Section 6. The Lessee shall have the right at its expense to make
alterations, improvements or additions to the interior of the demised premises,
provided that:

      (a) No such alteration, addition or improvement shall lessen the fair
market value of the demised premises or the Building and any such alteration,
addition or improvement shall be done in accordance with all applicable law, in
a good and workmanlike manner with good quality materials and shall not impair
the safety of the structure of the Building.

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      (b) Any such alteration, addition, or improvement shall be made in
accordance with plans and specifications which must have the written approval of
the Lessor before any work shall be commenced, such approval, with respect to
non-structural alterations, not to be unreasonably withheld. With respect to
structural alterations, improvements or additions, Lessor shall have absolute
discretion to withhold or grant its consent.

      (c) Prior to the commencement of work on any such alteration, addition, or
improvement, the plans and specifications covering the same shall have been
submitted to and approved by:

            1. All municipal or other governmental departments or agencies
having jurisdiction over the subject matter thereof, and

            2. Any mortgagee having an interest in or lien upon the Building or
the Land, if required by the terms of the mortgage.

      (d) The Lessee shall pay the increased premium, if any, for the insurance
coverage of the demised premises or the Building resulting from any additional
risk during the course or construction or installation of any such alteration,
addition, or improvement or resulting from such alteration, addition or
improvement.

      All additions, improvements and fixtures (other than the usual trade
fixtures, furniture and equipment installed by the Lessee which may be removed
from the demised premises without injury thereto) which may be made or installed
by either the Lessor or the Lessee and which are attached to a floor, wall or
ceiling, including any floor covering, shall remain upon the demised premises,
and at the expiration or earlier termination of this lease shall be surrendered
with the demised premises as a part thereof. However, the Lessor upon
termination of this lease may require the Lessee at Lessee's expense to restore
the demised premises to their condition at the commencement of this lease in
whole or in part.

      Any trade fixtures, furniture and equipment owned by the Lessee which may
be removed from the demised premises without injury thereto shall remain the
property of the Lessee and shall be removed by the Lessee from the demised
premises without injury thereto prior to the expiration or earlier termination
of this lease. In the event Lessee fails to remove said fixtures, furniture
and/or equipment prior to the expiration or earlier termination they shall be
deemed abandoned and may be disposed of by Lessor in any way it sees fit, and
Lessor shall not be liable to Lessee for any such disposal.

      Section 7. Without limiting Lessee's obligations in this Lease or
elsewhere, Lessee shall promptly, after notice from the Lessor, repair at its
own expense any damage to the exterior of the demised premises, the Building or
to the utilities serving

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the demised premises (including the HVAC system), or the Land (including without
limitation the parking areas, driveways, walkways, and grass and shrubs located
on the Land) caused by any act or negligence of the Lessee, its agents,
employees, licensees, suppliers, contractors, or guests.

      Section 8. It is understood that Lessor's obligations under this Article
VI are subject to the provisions and limitations set forth in Articles XV and
XVI.

                                   ARTICLE VII

                                    Utilities

      The Lessee shall pay when due all charges for utility services provided to
the demised premises including, without limitation, electricity, gas, water,
telephone, and the cost of fuel to heat or air-condition the demised premises.
If water consumed by the demised premises is not metered separately from water
consumed by the remainder of the Building, Lessee shall pay to Lessor, upon
being billed therefor by Lessor, Lessee's Pro Rata Share of the aforesaid. The
aforementioned share is based on the assumption that water in the demised
premises will be used only for ordinary drinking and lavatory purposes. If water
is consumed in the demised premises for other purposes or in excessive
quantities or if Lessee's heating and/or cooling requirements are materially
greater than that of other tenants or prospective tenants, then Lessee shall pay
to Lessor, on demand from time to time, charges for said additional water as
reasonably estimated by Lessor. Lessor reserves the right to install a water
meter to measure water consumption in the demised premises if not installed at
the Commencement Date. The Lessor shall not be liable for any interruption of
electricity, gas, water, telephone, sewage and/or septic system or other utility
service supplied to the demised premises and Lessor reserves the right to stop
any service or utility to the demised premises, when in Lessor's judgment it is
deemed necessary by reason of accident, emergency, repair work, or otherwise. No
such interruption or stoppage of utility service shall be deemed to be an
eviction of the Lessee or relieve Lessee from any of the Lessee's obligations
under this lease.

                                  ARTICLE VIII

                    Indemnity and Public Liability Insurance

      Section 1. The Lessee shall assume exclusive control of the demised
premises, and all tort liabilities with respect to the control or occupancy
thereof and shall save the Lessor harmless and indemnified from all injury,
loss, claims or damage of whatever nature to any person or property in or about
the demised premises, the Building and/or the Land, arising from any act,
omission or negligence of the Lessee or Lessee's subtenants or concessionaires
or the employees, agents, contractors, suppliers,

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licensees, invitees, or customers of any of the foregoing or otherwise resulting
from Lessee's use, maintenance and occupancy of the demised premises or any
thing or facility kept or used thereon. Upon request of Lessor, the Lessee shall
take over Lessor's defense in any action related to such matter for which Lessee
has agreed to indemnify Lessor.

      Section 2. Lessee agrees to maintain in full force during the term hereof
and any extensions thereof a policy of public liability and property damage
insurance under which the Lessor (and such other persons as are in privity of
estate with Lessor as may be set out in notice from the Lessor from time to
time) and Lessee are named as insureds, and under which the insurer agrees to
indemnify and hold Lessor and those in privity of estate with Lessor harmless
from and against all cost, expense and/or liability arising out of or based upon
any and all claims, accidents, injuries, and damages mentioned in Section 1 of
this Article VIII. Each such policy shall be non-cancellable with respect to the
Lessor and Lessor's said designees without thirty (30) days' prior written
notice to Lessor, and a duplicate original or certificate thereof shall be
delivered to Lessor. The minimum limits of liability of such insurance shall be
Three Million Dollars ($3,000,000) for injury (or death) to any one person, and
Three Million Dollars ($3,000,000) for injury (or death) to more than one
person, and Three Million Dollars ($3,000,000) with respect to damage to
property.

      Section 3. Neither the Lessor nor any agent or employee of the Lessor
shall be liable for any loss or damage to the person or property of the Lessee,
or of any subtenant, or concessionaire, or of any employee, customer, licensee,
invitee, contractor or supplier, or guest of any of the foregoing. Without in
any way limiting the generality of the foregoing, Lessor, its agents or
employees shall not be liable for any such damage resulting:

      (a) from the interruption to business resulting from theft, fire,
explosion, falling plaster, steam, gas, electricity, water, rain or snow or
leaks from any part of said demised premises, or from the pipes, appliances or
plumbing or from dampness or any other cause;

      (b) from any hidden defect in, under or upon the demised premises, the
Building or the Land; and/or

      (c) from acts or omissions of persons occupying adjacent premises or
otherwise entitled to use the Building and/or Land.

      Section 4. Lessor shall not be liable to Lessee for any compensation or
reduction of rent by reason of inconvenience or annoyance or for loss of
business arising from power losses or shortages or from the necessity of
Lessor's entering the demised premises for any of the purposes in this Lease
authorized or for repairing the demised premises or any portions of the Building
or Land in accordance herewith, nor shall any

                                       12
<PAGE>

such entry, interruption or similar event give rise to a claim in Lessee's favor
that such event constitutes actual or constructive, total or partial, eviction
from the demised premises, provided however, that to the extent that any such
entry or interruption materially impairs Lessee's operations at the demised
premises for the Permitted Uses for a period in excess of thirty (30) days, then
Lessee shall be entitled to a rent abatement in proportion to the reduction in
fair market rental value of the Premises occasioned by such entry or
interruption for that period of time after said thirty (30) day period during
which the entry or interruption continues.

                                   ARTICLE IX

                      Fire and Extended Coverage Insurance

      Section 1. The Lessor shall obtain the insurance for which Lessee makes
required payments to Lessor under Article III, Section 6.

      Section 2. The Lessee shall not acquire, by being named, at the election
of Lessor, as insured under any fire or extended coverage insurance on the
demised premises or the Building, any right to participate in the adjustment of
loss or to receive insurance proceeds and agrees upon request promptly to
endorse any checks or other instruments in payment of loss in which the Lessee
is named as payee.

      Section 3. The Lessee shall, at its own expense, maintain fire and
comprehensive casualty insurance with respect to, and in the amount of the full
replacement value of its own fixtures, merchandise, equipment and other property
contained in the demised premises, it being understood that all merchandise,
furniture, fixtures, effects and property of every kind of the Lessee which may
be in the demised premises, or the Building or on the Land shall be at the sole
risk and hazard of the Lessee.

                                    ARTICLE X

                    Hazardous Substances; Compliance With Law

      Section 1. Lessee shall not cause any hazardous or toxic wastes, hazardous
or toxic substances or hazardous or toxic materials (collectively, "Hazardous
Materials") to be used, generated or stored on, under or about, the Premises
(collectively, "Hazardous Materials Activities") without first receiving
Lessor's written consent, which consent shall not be unreasonably withheld if
the use, storage or generation of Hazardous Materials is necessary to conduct
Lessee's business and provided that Lessor receives such assurances as it shall
reasonably require against any loss or damage arising out of the use, storage or
generation of any Hazardous Materials. If Lessor consents to any Hazardous
Materials Activities, Lessee shall conduct them in strict compliance (at
Lessee's expense) with all applicable Regulations, as hereinafter defined, and
using all

                                       13
<PAGE>

necessary and appropriate precautions. Lessor shall not be liable to Lessee for
any Hazardous Materials Activities by Lessee, Lessee's employees, agents,
contractors, licensees or invitees, whether or not consented to by Lessor.
Lessee shall indemnify, defend with counsel reasonably acceptable to Lessor and
hold Lessor harmless from and against any claims, damages, costs and liabilities
arising out of Lessee's Hazardous Materials Activities. Lessee shall not dispose
of hazardous substances except in compliance with all applicable Regulations.
For the purposes hereof, Hazardous Materials shall include substances defined as
"hazardous substances", "toxic substances", or "hazardous wastes" in the federal
Comprehensive Environmental Response, Compensation and Liability Act of 1980, as
amended; the federal Hazardous Materials Transportation Act, as amended; and the
federal Resource Conservation and Recovery Act, as amended ("RCRA"); those
substances defined as "hazardous wastes" in the Massachusetts Hazardous Waste
Facility Siting Act, as amended (Massachusetts General Laws Chapter 21D); those
substances defined as "hazardous materials" or "oil" in Massachusetts General
Laws Chapter 29, as amended; and as such substances are defined in any
regulations adopted and publications promulgated pursuant to said laws
(collectively, "Regulations"). Prior to using, storing or maintaining any
Hazardous Materials on or about the Premises, Lessee shall provide to Lessor a
plan regarding Hazardous Waste management (a "Management Plan") which shall
include a list of the types and quantities of any Hazardous Materials to be
used, stored or maintained on or about the Premises, a description of the
precise location where such Hazardous Materials will be used, stored or
maintained, and a description of the steps Lessee shall take to inspect for,
detect, minimize, respond to and mitigate any release of Hazardous Materials.
Lessee shall at all times strictly comply with the Management Plan. Lessee shall
also provide Lessor a copy of any Hazardous Materials inventory statement
required by any applicable Regulations and any update filed in accordance with
any applicable regulations. If Lessee's activities violate or create a risk of
violation of any Regulations or the Management Plan, Lessee shall cease such
activities immediately. Lessee shall immediately notify Lessor both by telephone
and in writing of any spill or unauthorized discharge of Hazardous Materials or
of any condition constituting an "imminent hazard" under any Regulations.
Lessor, and Lessor's representatives and employees, may enter the Premises at
any time by appointment arranged one day in advance during the Term to inspect
Lessee's compliance herewith, and may disclose any violation of any Regulations
to any governmental agency with jurisdiction. Lessee shall not be responsible
for Hazardous Materials existing at the demised premises prior to the term of
this Lease. Lessee has been provided with a copy of "Report on Oil and Hazardous
Material Site Evaluation 33 Manning Road, Billerica, Massachusetts", dated July
1999 and prepared by Haley & Aldrich, Inc. (the "Environmental Report") and
Lessor has no actual knowledge of the existence of Hazardous Materials at the
demised premises which are not disclosed in the Environmental Report.

                                   ARTICLE XI

                            Assignment or Subletting

                                       14
<PAGE>

      Section 1. Lessee shall not assign, transfer, mortgage or pledge this
Lease or grant a security interest in Lessee's rights hereunder, or sublease
(which term shall be deemed to include the granting of concessions and licenses
and the like) or permit anyone other than Lessee to occupy all or any part of
the demised premises or suffer or permit this Lease or the leasehold interest
hereby created or any other rights arising under this Lease to be assigned,
transferred or encumbered, in whole or in part, whether voluntarily,
involuntarily or by operation of law, unless, in each instance (i) the prior
written consent of Lessor thereto shall have been obtained, which may be
withheld in Lessor's sole discretion, (ii) any defaults then existing with
respect to the obligations of Lessee under this Lease shall have been cured,
(iii) the rental rate of any such sublease is equal to or greater than the
rental rate under this Lease for the period of this Lease corresponding to the
term of the sublease, and (iv) in the case of a proposed assignment, sublease or
occupancy by another person or entity, the proposed assignee, sublessee, or
occupant is qualified to do business in Massachusetts and has a sufficient
financial net worth to satisfy the obligations of Lessee hereunder, and such
assignee, sublessee, or occupant executes and delivers to Lessor an agreement
satisfactory to Lessor by which such assignee, sublessee or occupant shall be
bound by and shall assume all the obligations of Lessee under this Lease
relating to the portion or all of the Premises acquired by such assignee,
sublessee or occupant. Notwithstanding anything to the contrary contained
herein, Lessee shall have the right to assign its interest in this Lease to an
entity which holds the controlling interest in Lessee or of which Lessee holds
the controlling interest, provided that (i) any defaults then existing with
respect to the obligations of Lessee under this Lease shall have been cured, and
(ii) the proposed assignee is qualified to do business in Massachusetts and has
a financial net worth at least equal to that of Lessee as of the date of this
Lease and as of the date of such proposed assignment, and such assignee executes
and delivers to Lessor an agreement satisfactory to Lessor by which such
assignee shall be bound by and shall assume all the obligations of Lessee under
this Lease.

      As used herein, "controlling interest" shall mean ownership of fifty-one
percent (51%) or more of the outstanding voting stock of the particular entity.

      Section 2. If for any assignment or sublease or occupancy by another,
Lessee receives rent or other consideration, either initially or over the term
of the assignment, sublease or occupancy, in excess of the rent called for
hereunder, or in case of a sublease of part of the demised premises, in excess
of such rent fairly allocable to the part so subleased, after appropriate
adjustments to assure that all other payments called for hereunder are
appropriately taken into account, Lessee shall pay to Lessor, as additional
rent, the excess of each such payment of rent or other consideration received by
Lessee promptly after its receipt.

      Section 3. In the event of a proposed assignment of this Lease, or in the
event of one or more proposed sublettings which, when aggregated with any
existing or

                                       15
<PAGE>

proposed sublettings result in existing or proposed subletting of 25% or more to
the rentable area of the demised premises for any period of time, Lessee's
request for Lessor's consent shall constitute an offer to Lessor to delete from
the Premises demised under this Lease, for the balance of the Term, the area
which is proposed to be subleased, which offer landlord may accept within 30
days after receipt. In the event that Landlord accepts such offer, the
description of the Premises shall be deemed to be amended by deleting therefrom
the area proposed to be subleased or assigned, and the Lessee's Pro Rata Share
shall be re-calculated in the manner described in Section hereof. Lessor's
failure to accept Lessee's offer to terminate shall not constitute a consent to
the proposed assignment.

      Section 4. For the purposes of this Article XI, the transfer in the
aggregate in any one year of 20% or more in interest in Lessee (whether stock,
partnership interest or other form of ownership or control) by any person or
persons having an interest in ownership or control of Lessee shall be deemed an
assignment of this Lease. The preceding sentence shall not apply to the initial
Lessee named herein if such Lessee is a corporation and the outstanding voting
stock thereof is listed on a recognized securities exchange.

      Section 5. Any attempted assignment, transfer, mortgage, pledge, grant of
security interest, sublease or other encumbrance, except as permitted by this
Article XI, shall be void. No assignment, transfer, mortgage, grant of security
interest, sublease or other encumbrance, whether or not approved, and no
indulgence granted by Lessor to any assignee, sublessee or occupant shall in any
way impair Lessee's continuing primary liability (which after an assignment or
subletting shall be joint and several with the assignee or sublessee) of Lessee
hereunder, and no approval in a particular instance shall be deemed to be a
waiver of the obligation to obtain Lessor's approval in any other case.

                                   ARTICLE XII

                                  Subordination

      Section 1. The Lessee shall from time to time, within ten (10) days
written demand of Lessor, either (as demanded by Lessor) subordinate this lease
or make this lease superior to any existing and/or future Mortgage heretofore or
hereafter placed upon the Land and to any renewal, modification, replacement or
extension of such Mortgage, and to any and all advances made or to be made
thereunder, provided that said Mortgagee enters into an agreement with Lessee by
the terms of which the Mortgagee under said Mortgage will agree that in the
event of foreclosure thereof, said Mortgagee will not disturb the possession of
the Lessee under the Lease so long as the Lessee is not in default hereunder and
the Lessee will agree to recognize the holder of such Mortgage as the Lessor in
such event, which agreement shall be made expressly binding upon the successors
and assigns of the Lessee, and the Mortgagee and upon

                                       16
<PAGE>

anyone purchasing said demised premises or Building at any foreclosure sale.
Lessor shall have the right to subject the Land and the Building to any easement
which does not materially interfere with Lessee's use of the Premises pursuant
to this Lease and Lessee hereby agrees that it shall subordinate its interest in
this Lease to any such easement upon written request of Lessor. The Lessee and
the Lessor agree to execute and deliver any instruments necessary to carry out
the agreements in this Section contained.

      Section 2. If any Mortgagee elects, by written notice given to the Lessee,
to have this Lease and the interest of the Lessee hereunder superior to any such
Mortgage then this Lease and the interest of the Lessee hereunder shall be
deemed superior to any such Mortgage, whether this Lease was executed before or
after such Mortgage.

      Section 3. Lessee will, upon request by Lessor or any Mortgagee, from time
to time, execute and deliver to such party (a) an "Estoppel Letter", so-called,
certifying that this Lease is unmodified and in full force and effect and that
Lessee has no defenses, offsets or counterclaims against its obligations to pay
the Annual Base Rent and additional rent hereunder and to perform its other
covenants under this Lease and that there are no uncured defaults of Lessor or
Lessee under this Lease (or, if there have been any modifications that the same
is in full force and effect as modified and stating the modifications and, if
there are any defenses, offsets, counterclaims, or defaults, setting them forth
in reasonable detail), and the dates to which the Annual Base Rent, additional
rent and other charges have been paid, and such other matters as a mortgagee or
purchaser of the demised premises may reasonably request and/or (b) a copy of
every notice of default delivered by Lessee to Lessor at the same time and in
the same manner as to Lessor (provided that the failure to provide such notice
shall not subject Lessee to termination of this Lease, provided still further
that Lessee shall not in any event have the right to terminate this Lease or
claim a constructive eviction hereunder until a copy of such notice of default
has been given to such Mortgagee and such Mortgagee has had a reasonable
opportunity to cure the default, and if possession of the demised premises is
required to cure the default, a reasonable opportunity to acquire possession of
the demised premises) and/or (c) an agreement consenting to an assignment of
this Lease to such party and acknowledging such assignment.

      Section 4. For purposes hereof, the term "Mortgage" shall mean any real
estate mortgages, ground leases, deeds of trust, security agreements or
indentures affecting the Land or the Building, and the term "Mortgagee" shall
include the holder of any such real estate mortgage, any ground lessor or any
trustees or holders of any such security agreements or indentures.

                                  ARTICLE XIII

                                    Self-Help

                                       17
<PAGE>

      If the Lessee shall default in the performance or observance of any
agreement or condition in this lease contained on its part to be performed or
observed, and shall not cure such default within thirty (30) days after notice
from Lessor specifying the default Lessor may, at its option, without waiving
any claim for breach of agreement, at any time thereafter cure such default for
the account of Lessee, and make all necessary payments in connection therewith,
including but not limiting the same to reasonable counsel fees, costs or charges
of or in connection with any legal action which may have been brought, and any
amount paid by Lessor in so doing shall be deemed paid for the account of Lessee
and Lessee agrees to reimburse Lessor therefor with interest thereon at a rate
equal to the Prime Rate (as hereinafter defined) in effect from time to time,
plus 4 percentage points, such sums payable by Lessee to Lessor to be deemed
additional rent, provided that Lessor may cure any such default as aforesaid
prior to the expiration of any waiting or cure period but after Lessor has
exerted reasonable efforts to give actual notice (by telephone or otherwise) if
the curing of such default prior to the expiration of said waiting or cure
period is reasonably necessary to protect the real estate or Lessor's interest
therein, or to prevent injury or damage to persons or property. As used herein,
the "Prime Rate" shall mean the rate of interest announced from time to time as
the prime rate of interest by Fleet Bank (or any successor institution thereto).

                                   ARTICLE XIV

                              Waiver of Subrogation

      Lessor and Lessee each hereby releases the other from any and all
liability or responsibility to the other (or anyone claiming through or under
them by way of subrogation or otherwise) for any loss or damage to the demised
premises or property thereon against which the waiving party is protected by
insurance, even if such loss or damage shall have been caused by the fault or
negligence of the other party, or anyone for whom such party may be responsible,
provided, however, that this release shall be applicable and in force and effect
only with respect to loss or damage occurring during such time as the releasor's
policies shall contain a clause or endorsement to the effect that any such
release shall not adversely affect or impair said policies or prejudice the
right of the releasor to recover thereunder. Lessor and Lessee each hereby agree
that it shall cause such a clause or endorsement to be included in its insurance
policies with respect to the demised premises, if available, and, if necessary,
pay any additional premium that may be charged therefor.

                                   ARTICLE XV

                              Damage by Fire, Etc.

      Section 1. If the demised premises or the Building shall be damaged or
destroyed by fire, windstorm or any other insured casualty, the Lessee shall

                                       18
<PAGE>

immediately give notice thereof to the Lessor and unless this Lease is
terminated as hereinafter provided the Lessor at its own expense shall repair or
rebuild the same so as to restore the demised premises to substantially the same
condition they were in immediately prior to such damage or destruction, subject,
however, to zoning and building laws then in existence, provided that the Lessor
shall not be responsible for any delay in such repair or reconstruction as
described in Section 14 of Article XXII hereof, and provided further that Lessor
shall not be required to expend more than the net amount of insurance proceeds,
if any, received by Lessor for such purposes, it being understood that the
application of insurance proceeds is subject to the right of any mortgagee of
the demised premises.

       Section 2. If either the demised premises or the Building shall be
damaged or destroyed to the extent of twenty percent (20%) or more on a square
footage basis by any cause (whether insured against by the Lessor or not), the
Lessor may elect by written notice to the Lessee either to terminate this lease
or to repair or rebuild on the conditions set forth in Section 1. Further, if
the demised premises are so destroyed, Lessee may, by notice given to Lessor
within 45 days of such damage, notify Lessor of its desire to terminate this
Lease ("Lessee's Termination Notice"). If such Lessee's Termination Notice is
given this Lease shall terminate 60 days after such notice is given unless,
within 60 days after such notice is given, Lessor delivers to Lessee its
certification (a "Restoration Notice") that it intends to cause the demised
premises or the Building to be restored to substantially the condition they were
in prior to such damage within 270 days of the event giving rise to such notice.
If Lessor gives a Restoration Notice and thereafter substantially completes the
restoration of the demised premises and the Building (except for items of work
and mechanical adjustment which can be completed without substantial
interference to Lessee's use of the demised premises) in accordance with Section
1 above within said 270 day period, which 270 day period will be extended for
any period of delay caused by a Force Majeure Event (but not beyond 365 days in
the aggregate), this Lease shall remain in full force and effect,
notwithstanding Lessee's Termination Notice, and if such restoration is not
substantially completed within said 270 day period (as the same may be extended
due to a Force Majeure Event), then Lessee shall have the right to terminate
this Lease by written notice given within thirty (30) days of the expiration of
said 270 day period (as the same may be extended due to a Force Majeure Event).

      Section 3. If the demised premises or the Building shall, within the last
year of the original term of this Lease or the last year of any extended term
hereof, be damaged or destroyed by any cause to such extent that the same cannot
be reasonably expected to be restored to substantially the same condition as
prior to such damage or destruction within ninety (90) days from the time that
such repair or restoration work would be commenced then the Lessor shall have
the right to terminate this Lease by notice to the Lessee given within sixty
(60) days after the occurrence of such damage or destruction.

                                       19
<PAGE>

      Section 4. In the event that the demised premises or the Building are
damaged or destroyed by any cause, then, unless this Lease is terminated as
above provided, the Lessee shall upon substantial completion of the repairs and
restoration necessitated by such casualty continue to operate and use the
demised premises for the Permitted Uses.

      Section 5. If this Lease is not terminated as above provided, then from
and after such damage which is material and until the demised premises are
restored as above provided, the rent reserved herein shall abate, either wholly
or proportionately, according to the nature and extent of the injury.

                                   ARTICLE XVI

                                 Eminent Domain

      Section 1. If as a result of any taking by eminent domain which shall be
deemed to include a voluntary conveyance in lieu of a taking the total floor
area remaining in the demised premises shall be reduced by twenty (20%) percent
or more of the total floor area in the demised premises at the commencement of
the term hereof, then at the election of either the Lessor or Lessee,
exercisable by written notice given to the other within ninety (90) days after
the date of the filing of the notice of such taking this Lease may be terminated
as of the date when the Lessee is required to vacate the demised premises or the
portion thereof so taken, notwithstanding that the entire interest of the Lessor
may have been divested by such taking, and if following any such taking neither
the Lessor nor Lessee terminates this Lease, then the Lessor, at the Lessor's
expense but only to the extent of the award actually received by the Lessor for
any such taking (subject to the rights of any first mortgagee of the demised
premises) and proceeding with all reasonable dispatch shall do such work as may
be required to put what may remain of the demised premises in proper condition
for the conduct of the Lessee's business, and the Lessee, upon substantial
completion by Lessor of such work as may be required to put what may remain of
the demised premises in proper condition for the conduct of the Lessee's
business, shall continue to operate and use the demised premises for the
Permitted Uses. From and after the date on which the Lessee is required to
vacate the portion of the demised premises so taken, a just proportion of the
rent reserved herein according to the nature and extent of the taking of the
demised premises, shall be abated until the demised premises are restored to
such condition that the Lessee can commence business therein, and from and after
the date on which the Lessor shall restore the demised premises in the manner
above provided the rent shall be reduced in the proportion that the floor area
of the portion of the demised premises so taken bears to the floor area of the
demised premises at the commencement of the term hereof.

      Section 2. In the event of a taking, as defined herein, of 25% or more of
the Land, or 25% of the area of the Building and even though such taking does
not affect (20%) twenty percent or more of the floor area of the demised
premises, the Lessor shall

                                       20
<PAGE>

nonetheless have the right to terminate this lease by notifying the Lessee of
the Lessor's election to terminate within (90) days after the final
determination of the amount of the award, or to restore any part of the demised
premises so remaining and in the case of such restoration, the rent shall be
abated to the extent provided above. The Lessor reserves and excepts all rights
to damages to the Land, the Building, the demised premises and the leasehold
hereby created or awards with respect thereto, then or thereafter accruing, by
reason of any taking by eminent domain or by reason of anything lawfully done or
required by any public authority, and the Lessee grants to the Lessor all the
Lessee's rights, if any, to such damages except with respect to the value of its
personal property, trade fixtures and equipment and its relocation expenses to
the extent compensated by a separate award and shall execute and deliver to the
Lessor such further instruments of assignments thereof as the Lessor may from
time to time request.

                                  ARTICLE XVII

                                     Default

      Section 1. (a) If Lessee shall default in the performance of any of its
obligations to pay the Annual Base Rent or additional rent or any other sums due
hereunder and if such default shall continue for 7 days after notice from Lessor
designating such default (provided that it shall constitute a separate default
hereunder if Lessee shall receive more than two such notices with respect to
Annual Base Rent or additional rent or any other sums due hereunder within any
twelve-month period during the term of this Lease) or if within 30 days after
notice from Lessor to Lessee specifying any other default or defaults Lessee has
not commenced diligently to correct the default or defaults so specified or has
not thereafter diligently pursued such correction to completion, or (b) if
Lessee or any present or future guarantor of all or any portion of Lessee's
obligations under this Lease (a "Guarantor") becomes insolvent or fails to pay
its debts as they fall due, or (c) if a trust mortgage or assignment is made by
Lessee or by any Guarantor for the benefit of creditors, or (d) if Lessee or any
Guarantor proposes a composition, arrangement, reorganization or
recapitalization with creditors, or (e) if the leasehold estate under this Lease
or any substantial part of the property of Lessee or of any Guarantor is taken
on execution, or by other process of law, or is attached or subjected to any
other involuntary encumbrance, or (f) if a receiver, trustee, custodian,
guardian, liquidator or similar agent is appointed with respect to Lessee or any
Guarantor, of if any such person or a mortgagee, secured party or other creditor
takes possession of the demised premises or of any substantial part of the
property of Lessee or of any Guarantor, and, in either case, if such appointment
or taking of possession is not terminated within 30 days after it first occurs,
or (g) if a petition is filed by or with the consent of Lessee or of any
Guarantor under any federal or state law concerning bankruptcy, insolvency,
reorganization, arrangement, or relief from creditors, or (h) if a petition is
filed against Lessee or against any Guarantor under any federal or state law
concerning bankruptcy, insolvency, reorganization, arrangement, or relief from

                                       21
<PAGE>

creditors, and such petition is not dismissed within 30 days thereafter, or (i)
if Lessee or any Guarantor which is a corporation dissolves or is dissolved or
liquidates or adopts any plan or commences any proceeding, the result of which
is intended to include dissolution or liquidation, then and in any of such
cases, Lessor and the agents and servants of Lessor lawfully may, in addition to
and not in derogation of any remedies for any preceding breach of covenant,
immediately or any time thereafter and without demand or notice and with or
without process of law enter into and upon the demised premises or any part
thereof in the name of the whole or mail a notice of termination addressed to
Lessee, and repossess the same as of Lessor's former estate and expel Lessee and
those claiming through or under Lessee and remove its and their effects without
being deemed guilty of any manner or trespass and without prejudice to any
remedies which might otherwise be used for arrears of rent or prior breach of
covenant, and upon such entry or mailing as aforesaid this Lease shall
terminate, Lessee hereby waiving all statutory rights (including without
limitation rights of redemption, if any, to the extent such rights may be
lawfully waived) and Lessor, without notice to Lessee, may store Lessee's
effects, and those of any person claiming through or under Lessee at the expense
and risk of Lessee, and, if Lessor so elects, may sell such effects at public
auction or private sale and apply the net proceeds to the payment of all sums
due to Lessor from Lessee, if any, and pay over the balance, if any, to Lessee.

      Section 2. In the event that this Lease is terminated under any of the
provisions contained in Section 1 or shall be otherwise terminated for breach of
any obligation of Lessee, Lessee, covenants to pay forthwith to Lessor, as
compensation, the excess of the total rent reserved for the residue of the Term
over the rental value of the demised premises for said residue of the Term. In
calculating the rent reserved there shall be included, in addition to the Annual
Base Rent and additional rent, the value of all other considerations agreed to
be paid or performed by Lessee for said residue. Lessee further covenants as
additional and cumulative obligations after any such termination to pay
punctually to Lessor all the sums and to perform all the obligations which
Lessee covenants in this Lease to pay and to perform in the same manner and to
the same extent and at the same time as if this Lease had not been terminated
(provided that the foregoing sentence shall not entitle Lessee to double
recovery with respect to the payment or performance of Lessee's obligations
under this Lease). In calculating the amounts to be paid by Lessee pursuant to
the next preceding sentence Lessee shall be credited with the portion of any
amount paid to Lessor as compensation as in this Section 2 provided, allocable
to the corresponding portion of the Term and also with the net proceeds of any
rent obtained by Lessor by reletting the demised premises, after deducting all
Lessor's reasonable expenses in connection with such reletting, including,
without limitation, all repossession costs, brokerage commissions, fees for
legal services and expenses of preparing the demised premises for such
reletting, it being agreed by Lessee that Lessor may, but shall not be obligated
to, (i) relet the demised premises or any part or parts thereof, for a term or
terms which may at Lessor's option be equal to or less than or exceed the period
which would otherwise have constituted the balance of the Term and may grant
such concessions as Lessor in its reasonable judgment

                                       22
<PAGE>

considers advisable or necessary to relet the same, (ii) make such alterations,
repairs and decorations in the demised premises as Lessor in its reasonable
judgment considers advisable or necessary to relet the same, and (iii) keep the
demised premises vacant unless and until Lessor is able to rent the demised
premises to a Lessee which is at least as desirable and financially responsible
as Lessee is on the date of this Lease, on terms not less favorable to Lessor
than those of this Lease. No action of Lessor in accordance with the foregoing
or failure to relet or to collect rent under reletting shall operate or be
construed to release or reduce Lessee's liability as aforesaid.

      In lieu of any other damages or indemnity and in lieu of full recovery by
Lessor of all sums payable under all the foregoing provisions of this Section 2,
Lessor may by notice to Lessee, at any time after this Lease is terminated under
any of the provisions contained in Section 1 or is otherwise terminated for
breach of any obligation of Lessee and before such full recovery, elect to
recover, and Lessee shall thereupon pay, as liquidated damages, an amount equal
to the aggregate of the Annual Base Rent and additional rent accrued in the 12
months ended next prior to such termination plus the amount of rent of any kind
accrued and unpaid at the time of termination and less the amount of any
recovery by Lessor under the foregoing provisions of this Section 2 up to the
time of payment of such liquidated damages.

      Nothing contained in this lease shall, however, limit or prejudice the
right of Lessor to prove for and obtain in proceedings under any federal or
state law relating to bankruptcy or insolvency or reorganization or arrangement,
an amount equal to the maximum allowed by any statute or rule of law in effect
at the time when, and governing the proceedings in which, the damages are to be
proved, whether or not the amount be greater than the amount of the loss or
damages referred to above.

      Section 3. Any and all rights and remedies which Lessor may have under
this Lease, and at law and equity, shall be cumulative and shall not be deemed
inconsistent with each other, and any two or more of all such rights and
remedies may be exercised at the same time insofar as permitted by law.

      Section 4. Any consent or permission by Lessor to any act or omission
which otherwise would be a breach of any covenant or condition herein, or any
waiver by Lessor of the breach of any covenant or condition herein, shall not in
any way be held or construed (unless expressly so declared) to operate so as to
impair the continuing obligation of any covenant or condition herein, or
otherwise, except as to the specific instance, operate to permit similar acts or
omissions.

      The failure of the Lessor to seek redress for violation of, or to insist
upon the strict performance of, any covenant or condition of this Lease shall
not be deemed a waiver of such violation nor prevent a subsequent act, which
would have originally constituted a violation, from having all the force and
effect of an original violation. The receipt by Lessor of rent with knowledge of
the breach of any covenant of this Lease

                                       23
<PAGE>

shall not be deemed to have been a waiver of such breach by Lessor, or by
Lessee, unless such waiver be in writing signed by the party to be charged. No
consent or waiver, express or implied, by Lessor to or of any breach of any
agreement or duty shall be construed as a waiver or consent to or of any other
breach of the same or any other agreement or duty.

                                  ARTICLE XVIII

                                     Notices

      Any notice, request, demand or other communication required or permitted
by this lease shall, until either party notifies the other in writing of a
different address in accordance herewith, be deemed to be duly given if in
writing and sent by registered or certified first class mail, postage prepaid,
return receipt requested, addressed as follows.

      If to Lessor: addressed to the Lessor

            c/o CB Richard Ellis-NE Partners
            600 Atlantic Avenue, 22nd Floor
            Boston, MA 02110

      If to the Lessee: addressed to the Lessee at the Lessee's Notice Address.

                                   ARTICLE XIX

                                    Brokerage

      Lessor and Lessee each warrants and represents to the other that it has
not dealt with any broker in connection with this lease or the demised premises,
except only Broker and Grubb & Ellis and each agrees to defend, indemnify and
hold the other harmless from and against any and all claims for brokerage fees
and commissions (except with respect to (a) Broker, the fees of which shall be
paid by Landlord and (b) Grubb & Ellis, the fees of which will be paid by
Nordblom Company) by any broker claiming to have dealt with it in connection
with this Lease.

                                   ARTICLE XX

                         Term "Lessee's Pro Rata Share"

                                       24
<PAGE>

      Lessee and Lessor hereby agrees that the total leasable square footage of
the Premises, the total leasable square footage of the Building and the Lessee's
Pro Rata Share are all as set forth in Article I hereof. If any additions are
made to the Building, or if the description of the Premises is deemed to have
been modified pursuant to Section 3 of Article XI, then the Lessee's Pro Rata
Share shall mean a fraction, the numerator of which fraction shall be the then
total leasable square footage of the Premises and the denominator or which shall
be the then total leasable square footage of floor area of the Building.

                                   ARTICLE XXI

                                Security Deposit

      Simultaneously with the execution hereof, Lessee shall deposit with Lessor
a Security Deposit in the amount equal to the Security Deposit Amount, as
security for the punctual performance by Lessee of each and every obligation of
it under this Lease. Lessor may apply or retain all or any part of such Security
Deposit to cure any default or to reimburse Lessor for any sum which Lessor may
spend by reason of the default. In the case of every such application or
retention Lessee shall, within 10 days of demand, pay to Lessor the sum so
applied or retained, which shall be added to the Security Deposit so that the
same shall be restored to its original amount. Lessee shall not have the right
to require Lessor to call upon or apply the Security Deposit to any obligation
of Lessee. Upon any conveyance by Lessor of its interest under this Lease, the
Security Deposit may be delivered by Lessor to Lessor's grantee or transferee.
Upon any such delivery, Lessee hereby releases the Lessor originally named
herein from any liability with respect to the Security Deposit, and Lessee
agrees to look solely to such grantee or transferee; this provision shall also
apply to subsequent grantees and transferees. If at the end of the Term, Lessee
shall not be in default under this Lease, the Security Deposit, or any balance
thereof, shall be returned to Lessee, without interest.

                                  ARTICLE XXII

                            Miscellaneous Provisions

      Section 1. No consent or waiver, express or implied, by the Lessor to or
of any breach in the performance by the Lessee of its agreements hereunder shall
be construed as a consent or waiver to or of any other breach in the performance
by the Lessee of the same or any other covenant or agreement. No acceptance by
the Lessor of any rent or other payment hereunder, even with the knowledge of
any such breach, shall be deemed a waiver thereof nor shall any acceptance of
rent or other such payment in a lesser amount than is herein required to be paid
by the Lessee, regardless of any endorsement on any check or any statement in
any letter accompanying the payment of the same, be construed as an accord and
satisfaction or in any manner other than as a

                                       25
<PAGE>

payment on account by the Lessee. No reference in this lease to any sublessee,
licensee or concessionaire, or acceptance by the Lessor from other than the
Lessee of any payment due hereunder shall be construed as a consent by the
Lessor to any assignment or subletting by the Lessee, or give the Lessee any
right to permit another to occupy any portion of the demised premises except as
herein expressly provided. No waiver by the Lessor in respect of any one tenant
shall constitute a waiver with respect to any other tenant. Failure on the part
of the Lessor to complain of any action or non-action on the part of the Lessee
or to declare the Lessee in default, no matter how long such failure may
continue, shall not be deemed to be a waiver by the Lessor of any of its rights
hereunder.

      Section 2. In no case shall mention of specific instances under a more
general provision be construed to limit the generality of said provisions.

      Section 3. The delivery of keys to Lessor or any employees of Lessor or
the Lessor's agent or any employee thereof shall not operate as a termination of
this lease or surrender of the demised premises.

      Section 4. If any installment of rent base or additional is paid more than
10 days after the due date thereof, then at Lessor's election it shall bear
interest at the Prime Rate plus four percentage points, from such due date to
date of payment, which interest shall be immediately due and payable as
additional rent.

      Section 5. If the Lessee continues to occupy the demised premises after
the termination hereof, it shall have no more rights than a tenant by
sufferance, but shall be liable for twice the aggregate rental as above
determined during such occupancy, and shall be liable for any loss or expense
due to such holding over. Nothing in this section shall be construed to permit
such holding over.

      Section 6. If any provisions of this Lease or the application thereof to
any person or circumstance shall be to any extent invalid or unenforceable the
remainder of this Lease and the application to persons or circumstances other
than those as to which it is invalid or unenforceable shall be valid and be
enforced to the fullest extent permitted by law.

      Section 7. Lessor agrees that upon Lessee's paying the rent and performing
and observing the agreements, conditions and other provisions on its part to be
performed and observed Lessee shall and may peaceably and quietly have, hold and
enjoy the demised premises during the term of this Lease and any extension
thereof without any manner of hindrance or molestation from Lessor or anyone
claiming under Lessor, subject however, to the rights of holders of present and
future Mortgages and to the terms and provisions of this Lease.

                                       26
<PAGE>

       Section 8. The conditions and agreements in this Lease contained to be
kept and performed by the parties hereto shall be binding upon and inure to the
benefit of said respective parties, their legal representatives, successors and
assigns and the same shall be construed as covenants running with the land.
Wherever in this Lease reference is made to either of the parties, it shall be
held to include and apply to the successors and assigns of such party as if in
each case so expressed unless the context requires otherwise and regardless of
the number and gender of such party, provided however, that the term "Lessor" as
used in this Lease means only the owner for the time being of the Land, so that
in the event of any sale or sales of the Land and demised premises or of this
Lease, the Lessor shall be and hereby is entirely released of all covenants and
obligations of the Lessor hereunder.

      Section 9. This Lease shall constitute the only agreement between the
parties relative to the demised premises and no oral statements and no prior
written matter not specifically incorporated herein shall be of any force or
effect. In entering into this Lease the Lessee relies solely upon the
representations and agreements contained herein. This agreement shall not be
modified except by writing executed by both parties.

      Section 10. The section and article headings throughout this instrument,
are for convenience and reference only and shall in no way be held to limit,
define or describe the scope or intent of this Lease or in any way affect this
Lease.

      Section 11. If the Lessor shall at any time be an individual, joint
venture, tenancy in common, joint tenancy, limited liability company, firm or
partnership (general or limited), or a trust or trustees of a trust, it is
specifically understood and agreed that there shall be no personal liability of
any individual or any joint venturer, member, tenant, partner (general or
limited), trustee, shareholder, officer, beneficiary or holder of a beneficial
interest under any of the provisions hereof or arising out of the use or
occupation of the demised premises by Lessee. The obligations of Lessor shall in
all events be binding upon Lessor's equity in the Building and Land only, all in
accordance herewith. It is further understood and agreed that the liability of
any party who is a Lessor (whether the original Lessor or any successor Lessor)
shall be limited to defaults occurring or arising during the period for which
such party shall have been a Lessor and such party shall not be liable for
defaults occurring or arising at any time before such party obtained its
interest as Lessor or after such party disposed of its interest as Lessor.

      Section 12. Lessor's obligation to perform its covenants and agreements
hereunder is subject to the condition precedent that this Lease be approved by
the holder of any mortgage of which the demised premises are a part and by the
issuer of any commitment to make a mortgage loan which is in effect on the date
hereof. Unless Lessor gives Lessee written notice within 15 days after the date
hereof that such holder or issuer, or both, has disapproved this Lease, then
this condition shall be deemed to

                                       27
<PAGE>

have been satisfied or waived and the provisions of this Section 12 shall be of
no further force or effect.

      Section 13. This Lease shall be governed by and construed and enforced in
accordance with the laws of the Commonwealth of Massachusetts.

      Section 14. In any case where Lessor is required to do any act, delays
caused by or resulting from Acts of God, war, civil commotion, fire, flood or
other casualty, labor difficulties, shortages of labor, materials or equipment,
government regulations, unusually severe weather, difficulty in obtaining
governmental permits and approvals, or other causes beyond Lessor's reasonable
control (any of the foregoing being referred to herein as a "Force Majeure
Event") shall not be counted in determining the time during which work shall be
completed, whether such time be designated by a fixed date, a fixed time,
"promptly" or "a reasonable time", and such time shall be deemed to be extended
by the period of delay resulting from such cause.

      Section 15. Lessee shall provide Lessor with annual certified financial
statements within sixty (60) days after the close of Lessee's fiscal year.

      Section 16. Lessee shall not record this lease, but upon request of either
party, both parties shall execute and deliver a notice of lease, in form
satisfactory to Lessor and appropriate for recording; the costs of such notice
shall be born by the requesting party.

                                  ARTICLE XXIII

                        Prohibition of Lessee Abandonment

      Lessee shall not vacate the demised premises or abandon the demised
premises during the Original Term, and any extension thereof. At all times
during the Original Term, and any extension thereof, Lessee agrees (i) to keep
the demised premises adequately heated to the extent necessary to prevent the
pipes from freezing and to prevent deterioration of the demised premises, (ii)
to keep the demised premises adequately secure so as to prevent the entry of
unauthorized persons, and (iii) to occupy the demised premises.

                                    No Offer

      This submission of a draft of this Lease or a summary of some or all of
its provisions does not constitute an offer to lease the demised premises, it
being understood and agreed that neither Lessor nor Lessee shall be legally
obligated with respect to the obligations hereunder unless and until this Lease
has been executed by both Lessor and Lessee and a fully executed copy has been
delivered to both.

                                     Signage

                                       28
<PAGE>

      Subject to Lessor's approval of the design and placement therefor (which
shall not be unreasonably withheld), Lessee shall have the right to place an
exterior sign on the demised premises identifying Lessee. Prior to installation
thereof, such exterior sign must be approved by all municipal or other
governmental departments or agencies having jurisdiction over the subject matter
thereof and such sign must be in compliance with all federal, state and local
statutes, laws, ordinances and rules governing the same. At the expiration or
earlier termination of the term of this Lease, Lessee shall remove such sign and
shall repair any damage caused to the demised premises by such removal.

                                Extension of Term

      Provided that at the time Lessee gives notice of exercise of its rights
under this Section, and at the time that the term would have otherwise expired
but for the exercise of this Extension Option, there is no default under this
Lease, Lessee shall have the right to extend the term hereof (the "Extension
Option") for a period of five (5) years (the "Extension Term"). The Extension
Option shall be exercised by written notice given by Lessee to Lessor at least
twelve (12) months prior to the expiration of the term of this Lease. Upon
Lessee's giving such written notice, this Lease and the term hereof shall be
extended for the Extension Term without the necessity of execution of any
additional documents. The Extension Term shall be upon all the terms, conditions
and provisions of this Lease except that the Annual Base Rent during the
Extension Term shall be the fair market rental value ("Fair Rental Value") of
the demised premises as of the commencement of the Extension Term, determined as
provided below, but in no event shall the Annual Base Rent for the Extension
Term be less than the Annual Base Rent during the last year of the initial term
of this Lease. The term "Fair Rental Value" shall mean the market rental value
per annum for the demised premises. Lessor shall exercise reasonable efforts to
establish the Fair Rental Value of the demised premises for the Extension Term
and, if not agreed to by Lessee nine (9) months prior to the date on which the
Extension Term is to commence (such date nine (9) months prior to the
commencement of the Extension Term being referred to herein as the "Appraisal
Date"), such Fair Rental Value shall be determined in accordance with the
appraisal procedure set forth below. If the applicable Fair Rental Value has not
been determined as of the date the same is to become effective, Lessee shall pay
Lessor Annual Base Rent at the rate quoted by Lessor as the Fair Rental Value
until such determination is made. In the event it shall subsequently be
determined that the Fair Rental Value quoted (and reasonably determined) by
Lessor is in excess of the actual Fair Rental Value, Lessor shall credit the
amount of such overpayment against the next installments of Annual Base Rent
becoming due. In the event it should subsequently be determined that the Fair
Rental Value quoted by Lessor is less than the actual Fair Rental Value, Tenant
shall pay the difference to Lessor within fifteen (15) days of the determination
of the actual Fair Rental Value.

      If the parties have not agreed on the Fair Rental Value prior to the
Appraisal Date, then both Lessor and Lessee shall each appoint an appraiser
within fifteen (15)

                                       29
<PAGE>

days after the Appraisal Date. Within fifteen (15) days after the designation of
both appraisers, the two (2) appraisers shall conduct such hearings and
investigations as they may deem appropriate and shall, within thirty (30) days
after the designation of the two (2) appraisers determine the Fair Rental Value
and the two (2) appraisers shall give notice thereof (or notice of their
inability to reach agreement, as the case may be) to the parties hereto within
said thirty (30) day period and the agreement, if any, of the two (2) appraisers
shall be binding upon the parties hereto.

      In the event the two (2) appraisers are unable to reach agreement within
said thirty (30) day period aforesaid, the two (2) appraisers shall, within
forty-five (45) days after the designation of the two (2) appraisers designate a
third appraiser. If the two (2) appraisers shall fail to agree upon the
designation of such third appraiser within the forty-five (45) day period, then
they or either of them shall apply to the president of the Greater Boston Real
Estate Board or its successor, or on his or her failure, refusal or inability to
act, to a court of competent jurisdiction, for the designation of such third
appraiser.

      Within three (3) business days after the designation of the third
appraiser, the two parties shall submit their respective positions with respect
to the Fair Rental Value to the third appraiser; thereafter the third appraiser
shall conduct such hearings and investigations as he or she may deem appropriate
and shall, within fifteen (15) days after the designation of the third
appraiser, choose the determination of Fair Rental Value of the other two (2)
appraisers which is closest to the actual Fair Rental Value of the demised
premises. Within such fifteen (15) day period, the third appraiser shall give
notice thereof to the parties hereto and the third appraiser's determination
shall be binding upon the parties hereto.

      All appraisers with respect to the Fair Rental Value shall be appraisers
or other qualified real estate professionals who shall have had at least ten
(10) years continuous commercial real estate experience in the locality of the
demised premises. No appraiser shall have been an employee of the appointing
party, or an agent or contractor of the appointing party.

      The parties shall be entitled to present evidence to the appraisers in
support of their respective positions. The appraisers may not make any
determination inconsistent with any of the terms of this Lease. The appraiser
shall not have the power to add to, modify or change any of the provisions of
this Lease. The determination of the appraisers, as provided above, shall be
conclusive upon the parties and shall have the same force and effect as a
judgment made in a court of competent jurisdiction. Each party shall pay the
fees, costs and expenses of the appraiser appointed by such party and of the
attorneys and expert witnesses of such party, and one-half (1/2) of the other
fees, costs and expenses of the appraisal properly incurred hereunder.

                                       30
<PAGE>

EXECUTED under seal on the date first above written.

                                    LESSOR:

                                    ACP MANNING ASSOCIATES, LLC

                                    By: /s/ Roger W. Altreuter
                                        --------------------------------
                                        Name: Roger W. Altreuter
                                              --------------------------
                                        Title: Manager
                                               -------------------------

                                    By: /s/ [Illegible]
                                        --------------------------------
                                        Name: [Illegible]
                                              --------------------------
                                        Title: Manager
                                               -------------------------

                                    LESSEE:

                                    AMERICAN SCIENCE AND ENGINEERING,
                                    INC.

                                    By: /s/ [Illegible]
                                        --------------------------------
                                        Name:
                                              --------------------------
                                        Title: VP
                                               -------------------------

                                       31
<PAGE>

                                List of Exhibits

Exhibit A - Description of Land

Exhibit B - Plan of Demised Premises and Land

Exhibit C - HVAC Maintenance Schedule

                                       32
<PAGE>

                                    EXHIBIT A

                               Description of Land

                               (follows this page)

                                       33
<PAGE>

                                    EXHIBIT A

The land in Billerica, Middlesex County, Massachusetts, situated on the
Northwesterly side of Manning Road, shown as Lot 1B on a plan entitled "Plan of
Land in Billerica, Mass. Prepared for The 128 Trust Scale: 1 inch = 100 feet
February, 1973 Emmons Flemming & Bienvenu, Inc., Engineers and Surveyors,
Revised April 19, 1973," recorded in Plan Book 116, Plan 159, bounded according
to said plan as follows:

SOUTHEASTERLY:          by said Manning Road, in two courses measuring 265.54
                        feet and 133.78 feet, respectively;

SOUTHWESTERLY:          by other land now or formerly of The 128 Trust, 1,031.30
                        feet;

NORTHERLY:              by land of various owners as shown on said plan; in
                        varying courses measuring 59.70 feet, 40.93 feet, 70.52
                        feet, 207.17 feet and 97.41 feet, respectively; and

NORTHEASTERLY:          by Lot 1A on said plan, 816.13 feet.

Together with the benefit of the right to use as appurtenant thereto a sewer
easement 20 feet in width running from Middlesex Turnpike to the granted
premises, over the Southeasterly portion of Lot 1A as shown on the plan
hereinbefore referred to with the right to enter and re-enter said easement for
all maintenance purposes as set forth in the deed from Paul G. Yewell et al,
Trustees, which deed is dated May 10, 1973 and recorded in Book 2065, Page 34.
<PAGE>

                                    EXHIBIT B

                        Plan of Demised Premises and Land

                               (follows this page)

                                       34
<PAGE>

                      [GRAPHIC: PLOT PLAN 33 MANNING ROAD]
<PAGE>

                                    EXHIBIT C

                            HVAC Maintenance Schedule

      PERIODIC MAINTENANCE

      Perform the following inspection and service routine at the, beginning of
each cooling season:

      1.    Clean the condenser coil by hosing with cold water. Do no use hot
            water which can cause excessive pressure within the coil.

      2.    Remove any accumulation of dust and dirt from the casing of the
            unit.

      3.    Clean or replace the air filters.

      4.    Inspect the control panel wiring to make certain connections are
            tight and are intact.

      5.    Inspect the condensate drain pan and piping to make sure they are
            clear and will carry away all water.

      At the beginning of the heating season, perform the following inspection
and service routine:

      1.    Add a few drops of SAE No. 10 non-detergent oil to the combustion
            blower motor. WARNING: The use of a heavier grade oil may cause
            operating difficulties during cold weather.

      2.    Clean or replace the air filters.

      3.    Inspect the control panel wiring and the heating controls to make
            sure connections are tight and wiring insulation is intact.

      4.    Check the operation of the gas ignition system, and the spark
            electrode (is operating properly) and the setting of the limit
            control and make sure the evaporator-furnace fan is cycled at the
            correct cut-in and cut-out points.

                                       35
<PAGE>

      MONTHLY INSPECTIONS

      It is recommended that, once a month, the following inspections be
performed:

      1.    Clean or replace air filters.

      2.    Inspect and clean, if necessary, the condensate drain piping during
            the cooling season.

                                       36<PAGE>

                                                               Exhibit 10(c)(iv)

     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 30, 1999
                                                           REGISTRATION NO. 333-

--------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933
                     ---------------------------------------

                     AMERICAN SCIENCE AND ENGINEERING, INC.
             (Exact Name of Registrant as Specified in Its Charter)

       MASSACHUSETTS                                             04-2440991
----------------------------                          ------------------------
(State or Other Jurisdiction                                (I.R.S. Employer
of Incorporation or                                         Identification.No.)
Organization)

                   829 MIDDLESEX TURNPIKE, BILLERICA, MA 01821
               (Address of Principal Executive Offices) (Zip Code)

                                 ---------------

                     AMERICAN SCIENCE AND ENGINEERING, INC.
                       1999 COMBINATION STOCK OPTION PLAN
                            (Full Title of the Plan)

                            STEVEN R. LONDON, ESQUIRE
                         BROWN, RUDNICK, FREED & GESMER
                              ONE FINANCIAL CENTER
                           BOSTON, MASSACHUSETTS 02111
                     (Name and Address of Agent for Service)

                                 (617) 856-8200
          (Telephone Number, Including Area Code, of Agent for Service)

                                 ---------------

<TABLE>
<CAPTION>
                         CALCULATION OF REGISTRATION FEE

                                                        Proposed            Proposed
                                      Amount             Maximum        Maximum Aggregate
    Title of Each Class of            to be          Offering Price    Offering Price (1)          Amount of
 Securities to be Registered        Registered        Per Share (1)                            Registration Fee
---------------------------------------------------------------------------------------------------------------
<S>                                <C>                   <C>                 <C>                     <C>
Common Stock,                      600,000 (2)           $7.88(3)            $4,728,000(3)           $1,314.38
$.66 2/3 par value

Rights to Purchase                   600,000              0(5)                0(5)                   0(5)
Common Stock (4)
---------------------------------------------------------------------------------------------------------------
</TABLE>

      (1) Estimated solely for the purpose of determining the registration fee
pursuant to Rule 457(h) under the Securities Act of 1933, as amended.

      (2) Such presently indeterminable number of additional shares of Common
Stock are also registered hereunder as may be issued in the event of a merger,
consolidation, reorganization, recapitalization, stock dividend, stock split or
other similar change in Common Stock

      (3) Based upon the average high and low prices for the Registrant's Common
Stock, $.66 2/3 par value (the "Common Stock"), on November 26, 1999 as reported
by the American Stock Exchange.

      (4) Pursuant to a Rights Agreement entered into in 1998, one right (each a
"Right") is deemed to be delivered with each outstanding share of Common Stock.
The 600,000 Rights registered hereby consist of 600,000 Rights which may be
issued with shares of Common Stock issuable upon exercise of options granted or
to be granted under the Registrant's 1999 Combination Stock Option Plan.

      (5) The Rights are not separately transferable apart from the Common
Stock, nor are they exercisable until the occurrence of certain events.
Accordingly, no independent value has been attributed to the Rights.
<PAGE>

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents are hereby incorporated by reference into this
Registration Statement:

         (a)      The Registrant's latest Annual Report on Form 10-K for the
                  fiscal year ended March 31, 1999 filed pursuant to Section
                  13(a) or 15(d) of the Securities Exchange Act of 1934, as
                  amended (the "Exchange Act");

         (b)      All other reports filed by the Registrant pursuant to Section
                  13(a) or 15(d) of the Exchange Act since the end of the fiscal
                  year covered by the Registrant's annual report referred to in
                  (a) above; and

         (c)      The description of the Registrant's Common Stock contained in
                  the Registrant's Registration Statement on Form 8-A (File No.
                  001-06549) pursuant to the Exchange Act with the Securities
                  and Exchange Commission (the "Commission"), and the
                  description of the Rights contained in the Registrant's
                  Registration Statement on Form 8-A, filed on April 15, 1998,
                  with the Commission, and all amendments thereto and reports
                  filed for the purpose of updating such descriptions.

         All documents filed by the Corporation pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act, subsequent to the date hereof and prior
to the filing of a post-effective amendment which indicates that all securities
offered have been sold or which deregisters all securities then remaining
unsold, shall be deemed hereby incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents. Any
statement contained in a document incorporated or deemed to be incorporated by
reference herein shall be deemed to be modified or superseded for purposes of
this registration statement to the extent that a statement contained herein or
in any subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement.

Item 4.  DESCRIPTION OF SECURITIES.

         Not Applicable.

Item 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The validity of the shares of Common Stock to be issued in accordance
with the American Science and Engineering, Inc. 1999 Combination Stock Option
Plan has been passed

                                        3
<PAGE>

upon for the Registrant by Brown, Rudnick, Freed & Gesmer, One Financial Center,
Boston, Massachusetts 02111.

Item 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 67 of Chapter 156B of the Massachusetts General Laws permits the
indemnification of directors and officers to the extent authorized by the
Articles of Organization or By-Laws of a corporation or by a vote of the
stockholders. Except as otherwise provided by the Articles of Organization or
By-Laws, indemnification of persons who are not directors of a corporation may
be provided to the extent authorized by the directors. No indemnification may be
provided for any person with respect to any matter as to which he shall have
been adjudicated in any proceeding not to have acted in good faith in the
reasonable belief that his action was in the best interest of the corporation.

        Article VI of the Registrant's By-Laws provides, in substance, that the
Registrant shall indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending or completed action or suit, by
reason of the fact that he is or was serving as a director or officer of the
Registrant or is or was serving at the request of the Registrant as a director,
trustee or officer of another corporation or entity. The indemnification
provisions apply to expenses actually incurred by such person in connection with
any civil action, suit or proceeding to which such person may be made a party,
or by which such person shall be threatened, by reason of any alleged act or
failure to act in his present or former capacity as a director or officer of the
Registrant or as a director, trustee or officer of such affiliated corporation
or entity. No person, however, has the right to indemnification in relation to
any matter as to which such person shall have been finally adjudged in any legal
proceeding not to have acted in good faith and the reasonable belief that the
person's action was in the best interest of the Registrant. In the event of any
settlement of any action, suit or proceeding, the right to indemnification is
limited to matters as to which the Registrant is advised by counsel that such
settlement is reasonable and that such person has acted in good faith and the
reasonable belief that his action was in the best interest of the Registrant.
The right of indemnification contained in the Registrant's By-Laws is
non-exclusive and is in addition to any other rights such person may have.

         The Registrant has also entered into indemnification agreements with
all of its directors and executive officers (the "Indemnitees"). In general,
these agreements provide that the Registrant will indemnify and advance expenses
to the Indemnitees to the fullest extent permitted by law. More specifically,
the Registrant must indemnify the Indemnitees if, by reason of the Indemnitee's
corporate status, the Indemnitee is, or is threatened to be made, a party to or
is otherwise involved in any legal proceeding brought by: (1) persons other than
the Registrant; or (2) or in the right of the Registrant. The Indemnitee will
only be indemnified, however, if the Indemnitee acted in good faith and is
adjudged not to have received an improper personal benefit. In a claim brought
by or on behalf of the Registrant, no indemnification will be made if the
Indemnitee is adjudged to be liable to the Registrant unless a court deciding
the matter decides otherwise. Finally, notwithstanding the foregoing discussion,
if an Indemnitee is successful on the merits of a proceeding, the Indemnitee
will be indemnified to the maximum

                                        4
<PAGE>

extent permitted by law from all expenses, judgments, penalties, fines and
amounts paid in settlement, actually and reasonably incurred.

Item 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         Not Applicable.

                                        5
<PAGE>

Item 8.  EXHIBITS.

<TABLE>
<CAPTION>
NUMBER EXHIBIT    DESCRIPTION OF EXHIBIT                                                                      PAGE
<S>               <C>                                                                                          <C>
4.1               Restated Articles of Organization of the Registrant, as
                  amended by: (a) Articles of Amendment dated October 29, 1976;
                  (b) Articles of Amendment dated May 17, 1976; (c) Articles of
                  Amendment dated March 28, 1973; (d) Articles of Amendment
                  dated November 5, 1996 (each of the foregoing is filed as
                  Exhibit 4.1 to the Registrant's Registration Statement on Form
                  S-8 filed on May 28, 1997 with respect to the Registrant's
                  Executive Equity Incentive Plan); and (e) Certificate of Vote
                  of Directors Establishing a Class or Series of Stock dated
                  April 14, 1998 (filed as Exhibit 4.1 to the Registrant's
                  Registration Statement on Form S-8 filed on December 24, 1998
                  with respect to the Registrant's 1998 Non-Qualified Stock
                  Option Plan).                                                                                  *

4.2               By-Laws of the Registrant, as amended (filed as Exhibit 2(a)(iii) to
                  Registrant's  Registration Statement on Form S-7, Registration No. 2-56452 (the
                  "Form S-7")).                                                                                  *

4.3               Specimen  Certificate  of Common  Stock  (filed as Exhibit  2(a)(i) to the Form
                  S-7).                                                                                          *

4.4               Shareholder  Rights  Agreement (the "Rights  Agreement")  dated as of April 17,
                  1998 between  Registrant  and American  Stock  Transfer & Trust Co.,  Inc.,  as
                  Rights  Agent  (filed as Exhibit 4 to the  Current  Report on Form 8-K filed on
                  April 15, 1998).                                                                               *

5                 Legal Opinion of Brown, Rudnick, Freed & Gesmer.                                              11

23.1              Consent of Brown, Rudnick, Freed & Gesmer.                                                    **

23.2              Consent of Arthur Andersen LLP.                                                               15

24                Power of Attorney.                                                                           ***

99                American Science and Engineering, Inc. 1999 Combination Stock Option Plan.                     *
---------------------------------------------------
</TABLE>

*        Not filed herewith. In accordance with Rule 411(c) promulgated pursuant
         to the Securities Act of 1933, as amended, reference is made to the
         documents previously filed with the Securities and Exchange Commission
         which documents are hereby incorporated by reference.
**       Contained in Exhibit 5.
***      Included on Signature Page of this Registration Statement.

                                        6
<PAGE>

Item 9.  UNDERTAKINGS.

         (a)      The undersigned Registrant hereby undertakes:

                  (1)      To file, during any period in which offers or sales
                           are being made, a post-effective amendment to this
                           Registration Statement to include any material
                           information with respect to the plan of distribution
                           not previously disclosed in the Registration
                           Statement or any material change to such information
                           in the Registration Statement.

                  (2)      That, for the purpose of determining any liability
                           under the Securities Act of 1933, each such
                           post-effective amendment shall be deemed to be a new
                           registration statement relating to the securities
                           offered therein, and the offering of such securities
                           at that time shall be deemed to be the initial BONA
                           FIDE offering thereof.

                  (3)      To remove from registration by means of a
                           post-effective amendment any of the securities being
                           registered which remain unsold at the termination of
                           the offering.

         (b) The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial BONA FIDE offering thereof.

         (h) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 (the "Act") may be permitted to directors, officers and
controlling persons of the Registrant pursuant to the foregoing provisions, or
otherwise, the Registrant has been advised that in the opinion of the Securities
and Exchange Commission such indemnification is against public policy as
expressed in the Act and is, therefore, unenforceable. In the event that a claim
for indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.

                                        7
<PAGE>

                                   SIGNATURES

                                 THE REGISTRANT

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of Billerica, Commonwealth of Massachusetts, on November
30, 1999.

                                         American Science and Engineering, Inc.
                                         (Registrant)

                                              /s/ Ralph S. Sheridan
                                              --------------------------
                                              By: Ralph S. Sheridan, President

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Ralph S. Sheridan and Lee C. Steele, and
each of them (with full power to each of them to act alone), his and true and
lawful attorneys-in-fact and agents, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign any and all amendments (including post-effective amendments)
to this Registration Statement, and to file the same, with all exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, granting unto said attorneys-in-fact and agents, and each of them,
full power and authority to do and perform each and every act and thing
requisite and necessary to be done in and about the premises as fully to all
intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents, or any of them, or their
substitutes, may lawfully do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
NAME                                     CAPACITY                                      DATE
----                                     --------                                      ----
<S>                                      <C>                                           <C>
/s/ Ralph S. Sheridan                    President, Chief Executive                    November 30, 1999
---------------------------              Officer and Director
Ralph S. Sheridan                        (Principal Executive
                                         Officer)
</TABLE>

                                        8
<PAGE>

<TABLE>
<S>                                      <C>                                           <C>
/s/ Herman Feshbach                      Director                                      November 30, 1999
---------------------
Herman Feshbach

/s/ Roger P. Heinisch                    Director                                      November 30, 1999
---------------------
Roger P. Heinisch

/s/ Hamilton W. Helmer                   Director                                      November 30, 1999
---------------------
Hamilton W. Helmer

/s/ Donald J. McCarren                   Director                                      November 30, 1999
---------------------
Donald J. McCarren

/s/ William E. Odom                      Director, Chairman of the                     November 12, 1999
---------------------                    Board of Directors
William E. Odom

/s/ Carl W. Vogt                         Director                                      November 30, 1999
---------------------
Carl W. Vogt
</TABLE>

                                        9
<PAGE>

                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
NUMBER EXHIBIT    DESCRIPTION OF EXHIBIT                                                     PAGE

<S>               <C>                                                                        <C>
4.1               Restated Articles of Organization of the Registrant, as
                  amended by: (a) Articles of Amendment dated October 29, 1976;
                  (b) Articles of Amendment dated May 17, 1976; (c) Articles of
                  Amendment dated March 28, 1973; (d) Articles of Amendment
                  dated November 5, 1996 (each of the foregoing is filed as
                  Exhibit 4.1 to the Registrant's Registration Statement on Form
                  S-8 filed on May 28, 1997 with respect to the Registrant's
                  Executive Equity Incentive Plan); and (e) Certificate of Vote
                  of Directors Establishing a Class or Series of Stock dated
                  April 14, 1998 (filed as Exhibit 4.1 to the Registrant's
                  Registration Statement on Form S-8 filed on December 24, 1998
                  with respect to the Registrant's 1998 Non-Qualified Stock
                  Option Plan).                                                                *

4.2               By-Laws of the Registrant, as amended (filed as Exhibit
                  2(a)(iii) to Registrant's Registration Statement on Form S-7,
                  Registration No. 2-56452 (the "Form S-7")).                                  *

4.3               Specimen Certificate of Common Stock (filed as Exhibit 2(a)(i)
                  to the Form S-7). *

4.4               Shareholder Rights Agreement (the "Rights Agreement") dated as
                  of April 17, 1998 between Registrant and American Stock
                  Transfer & Trust Co., Inc., as Rights Agent (filed as Exhibit
                  4 to the Current Report on Form 8-K filed on April 15, 1998).                *

5                 Legal Opinion of Brown, Rudnick, Freed & Gesmer.                            11

23.1              Consent of Brown, Rudnick, Freed & Gesmer.                                  **

23.2              Consent of Arthur Andersen LLP.                                             15

24                Power of Attorney.                                                         ***

99                American Science and Engineering, Inc. 1999 Combination Stock
                  Option Plan.                                                                 *
---------------------------------------------------
</TABLE>

*        Not filed herewith. In accordance with Rule 411(c) promulgated pursuant
         to the Securities Act of 1933, as amended, reference is made to the
         documents previously filed with the Securities and Exchange Commission
         which documents are hereby incorporated by reference.
**       Contained in Exhibit 5.
***      Included on Signature Page of this Registration Statement.

                                       10
<PAGE>

                                   EXHIBIT (5)

                    OPINION OF BROWN, RUDNICK, FREED & GESMER

                                                              November 29, 1999

American Science and Engineering, Inc.
829 Middlesex Turnpike
Billerica, MA 01821

         Re:   American Science and Engineering, Inc.
               REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

         We have acted as legal counsel to American Science and Engineering,
Inc., a Massachusetts corporation (the "Company"), in connection with the
preparation and filing of a Registration Statement on Form S-8 (the
"Registration Statement") with the Securities and Exchange Commission under the
Securities Act of 1933, as amended (the "Act"), relating to 600,000 shares of
the Company's Common Stock (the "Common Stock"), $.66 2/3 par value (the
"Shares") and 600,000 Rights (as defined below).

         The Shares are issuable upon exercise of options granted pursuant to
the American Science and Engineering, Inc. 1999 Combination Stock Option Plan
(the "Plan"). The Rights are issuable pursuant to that certain Shareholder
Rights Agreement, dated as of April 17, 1998, between the Company and American
Stock Transfer and Trust Co., Inc. (the "Rights Agreement") providing, in
effect, for the delivery of a right (a "Right") to purchase one-thousandth of a
share of Series A Junior Participating Preferred Stock, no par value, of the
Company, along with each share of Common Stock issued by the Company pursuant
to, among other things, the Plan.

         In connection with this Opinion Letter, we have examined the documents
listed on Schedule A attached hereto (collectively, the "Documents").

         We have, without independent investigation, relied upon the
representations and warranties of the various parties as to matters of objective
fact contained in the Documents.

         We have not made any independent review or investigation of orders,
judgments, rules or other regulations or decrees by which the Company or any of
its property may be bound, nor have we made any independent investigation as to
the existence of actions, suits, investigations or proceedings, if any, pending
or threatened against the Company.

         With your concurrence, the opinions hereafter expressed, whether or not
qualified by language such as "to our knowledge," is based solely upon: (i) our
review of the Documents; (ii) discussions with those of our attorneys who have
given substantive legal representation to the

                                       11
<PAGE>

Company in connection with the Registration Statement; and (iii) such review of
published sources of law as we have deemed necessary.

         This firm, in rendering legal opinions, customarily makes certain
assumptions which are described in Schedule B hereto. In the course of our
representation of the Company in connection with the Registration Statement,
nothing has come to our attention which causes us to believe reliance upon any
of those assumptions is inappropriate, and, with your concurrence, the opinions
hereafter expressed is based upon those assumptions. For purposes of those
assumptions, the Enumerated Party referred to in Schedule B is the Company.

         Our opinions hereafter expressed is limited to the laws of the
Commonwealth of Massachusetts and Federal law. We express no legal opinions upon
any matter other than as explicitly addressed in numbered paragraphs 1 and 2
below, and our express opinions therein contained shall not be interpreted to be
implied opinions upon any other matter.

         Based upon and subject to the foregoing, we are of the opinion that:

         1. The Shares have been duly authorized for issuance and, when issued
and paid for in accordance with the terms of the Plan, will be validly issued,
fully paid and nonassessable.

         2. The Rights have been duly authorized for issuance and, when issued
in accordance with the Rights Agreement, will be validly issued, fully paid and
nonassessable.

         We hereby consent to the filing of this opinion as an Exhibit to the
Registration Statement and to the reference to this firm wherever it appears in
the Registration Statement.

                                      Very truly yours,

                                      BROWN, RUDNICK, FREED & GESMER

                                      By:   Brown, Rudnick, Freed & Gesmer, P.C.
                                            a partner

                                      By:   /s/ Steven R. London
                                      -----------------------------------------
                                      Steven R. London, duly authorized

                                       12
<PAGE>

                                   SCHEDULE A

                                LIST OF DOCUMENTS

         In connection with the Opinion Letter to which this Schedule A is
attached, we have reviewed the following Documents. However, except as otherwise
expressly indicated, we have not reviewed any documents, instruments or
agreements referred to in or listed upon any of the following Documents:

         (i)      a copy of the Restated Articles of Organization of the
                  Company, as amended, as certified by the Secretary of State of
                  the Commonwealth of Massachusetts and a certificate of the
                  Clerk of the Company that there have been no further
                  amendments thereto;

         (ii)     a copy of the By-Laws of the Company, as amended, certified by
                  the Clerk of the Company as presently being in effect;

         (iii)    the proceedings of the stockholders and directors of the
                  Company pertaining to the Plan and the Rights Agreement and a
                  certificate of the Clerk of the Company as to certain
                  resolutions of the directors of the Company;

         (iv)     a certificate dated as of November 29, 1999 of the Secretary
                  of State of the Commonwealth of Massachusetts as to the good
                  standing of the Company;

         (v)      the Plan;

         (vi)     the Rights Agreement; and

         (vii)    the Registration Statement.

                                       13
<PAGE>

                                   SCHEDULE B

                         BROWN, RUDNICK, FREED & GESMER
                              STANDARD ASSUMPTIONS

         In rendering legal opinions in third party transactions, Brown,
Rudnick, Freed & Gesmer makes certain customary assumptions described below:

         1.       Each natural person executing any of the Documents has
                  sufficient legal capacity to enter into such Documents.

         2.       Each person, other than the Enumerated party, has all
                  requisite power and authority and has taken all necessary
                  corporate or other action to enter into the Documents to which
                  it is a party, or by which it is bound, to the extent
                  necessary to make the Documents enforceable against it.

         3.       Each person other than the Enumerated Party has complied with
                  all legal requirements pertaining to its status as such status
                  relates to its rights to enforce the Documents against the
                  Enumerated Party.

         4.       Each Document is accurate, complete and authentic, each
                  original is authentic, each copy conforms to an authentic
                  original and all signatures are genuine.

         5.       All official public records are accurate, complete and
                  properly indexed and filed.

         6.       There has not been any mutual mistake of fact or
                  misunderstanding, fraud, duress, or undue influence by or
                  among any of the parties to the Documents.

         7.       The conduct of the parties to the Documents has complied in
                  the past and will comply in the future with any requirement of
                  good faith, fair dealing and conscionability.

         8.       The Enumerated Party will obtain all permits and governmental
                  approvals required in the future and take all actions
                  similarly required relevant to its performance of its
                  obligations under the Documents.

         9.       All parties to or bound by the Documents will act in
                  accordance with, and will refrain from taking any action that
                  is forbidden by, the terms and conditions of the Documents.

         10.      There are no agreements or understandings among the parties to
                  or bound by the Documents not reflected in the Documents, and
                  there is no usage of trade or course of prior dealing among
                  such parties, that would define, modify, waive, or qualify the
                  terms of any of the Documents.

                                       14
<PAGE>

                                 EXHIBIT (23.2)

                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

         As independent public accountants, we hereby consent to the
incorporation by reference into this Registration Statement of our report
dated May 15, 1999 included in American Science and Engineering, Inc.'s
Annual Report on Form 10-K for the fiscal year ended March 31, 1999 and to
all references to our Firm included in this Registration Statement.

                                                   /s/ Arthur Andersen LLP
                                                   -----------------------------
Boston, Massachusetts
November 29, 1999

                                       15
<PAGE>

                                  EXHIBIT (99)

                     AMERICAN SCIENCE AND ENGINEERING, INC.

                       1999 COMBINATION STOCK OPTION PLAN

      SECTION I. PURPOSE OF THE PLAN.

         The purpose of this American Science and Engineering, Inc. 1999
Combination Stock Option Plan (the "1999 Plan") are (i) to provide long-term
incentives and rewards to those employees (the "Employee Participants") of
American Science and Engineering, Inc. (the "Corporation") and its subsidiaries
(if any), and any other persons who are not directors of the Corporation (the
"Non-employee Participants") who are in a position to contribute to the
long-term success and growth of the Corporation and its subsidiaries, (ii) to
assist the Corporation in retaining and attracting executives and employees with
requisite experience and ability, and (iii) to associate more closely the
interests of such executives and employees with those of the Corporation's
stockholders.

      SECTION II. DEFINITIONS.

      "CODE" is the Internal Revenue Code of 1986, as amended from time to time.

      "COMMON STOCK" is the $.66 2/3 par value common stock of the Corporation.

      "COMMITTEE" is defined in Section III, paragraph (a).

      "CORPORATION" is defined in Section I.

      "CORPORATION ISOS" are all the stock options (including the 1999 Plan
ISOs) which (i) are Incentive Stock Options and (ii) are granted under any plans
(including this 1999 Plan) of the Corporation, a Parent Corporation and/or a
Subsidiary Corporation.

      "EMPLOYEE PARTICIPANTS" is defined in Section I.

      "FAIR MARKET VALUE" of any property is the value of the property as
reasonably determined by the Committee.

      "INCENTIVE STOCK OPTION" is a stock option that is treated as an
incentive stock option under Section 422 of the Code.

      "1934 ACT" means the Securities Exchange Act of 1934, as amended, or
any similar or successor statute, and any rules, regulations, or policies
adopted or applied thereunder.

      "1999 PLAN" is defined in Section I.

                                       16
<PAGE>

      "1999 PLAN ISOS" are Stock Options which are Incentive Stock Options.

      "NON-EMPLOYEE PARTICIPANTS" is defined in Section I.

      "NON-QUALIFIED OPTION" is a Stock Option which does not qualify as an
Incentive Stock Option or for which the Committee provides, in the terms of such
option and at the time such option is granted, that the option shall not be
treated as an Incentive Stock Option.

      "PARENT CORPORATION" has the meaning provided in Section 424 (e) of the
Code.

      "PARTICIPANTS" are all persons who are either Employee Participants or
Non-employee Participants.

      "PERMANENT AND TOTAL DISABILITY" has the meaning provided in Section 22
(e) (3) of the Code.

      "RULE 16b-3" means Securities and Exchange Commission Rule 16b-3.

      "SECTION 16" means Section 16 of the 1934 Act, or any similar or
successor statute, and any rules, regulations, or policies adopted or applied
thereunder.

      "STOCK OPTIONS" are rights granted pursuant to this 1999 Plan to
purchase shares of Common Stock at a fixed price.

      "STOCKHOLDER APPROVAL" means the affirmative vote of at least a
majority of the shares of Common Stock present and entitled to vote at a duly
held meeting of the stockholders of the Corporation, unless a greater vote is
required by state law or Section 16, if applicable to the Corporation, in which
case such greater requirement shall apply. Stockholder approval may be obtained
by written consent or other means, to the extent permitted by applicable state
law.

      "SUBSIDIARY CORPORATION" has the meaning provided in Section 424 (f) of
the Code.

      "TEN PERCENT STOCKHOLDER" means, with respect to a 1999 Plan ISO, any
individual who directly or indirectly owns stock possessing more than 10% of the
total combined voting power of all classes of stock of the Corporation or any
Parent Corporation or any Subsidiary Corporation at the time such 1999 Plan ISO
is granted.

      SECTION III. ADMINISTRATION.

      (a) THE COMMITTEE. This 1999 Plan shall be administered by the Board of
Directors or by a compensation committee consisting solely of two or more
"non-employee directors", as defined in Rule 16b-3, who shall be designated by
the Board of Directors of the Corporation (the administering body is hereafter
referred to as the "Committee"). The Committee shall serve at the pleasure of
the Board of Directors, which may from time to time, and in its sole discretion,
discharge any member, appoint additional new members in substitution for those
previously appointed and/or fill vacancies however caused. A majority of the

                                       17
<PAGE>

Committee shall constitute a quorum and the acts of a majority of the members
present at any meeting at which a quorum is present shall be deemed the action
of the Committee. No person shall be eligible to be a member of the Committee if
that person's membership would prevent the plan from complying with Rule 16b-3,
if applicable to the Corporation.

      (b) AUTHORITY AND DISCRETION OF THE COMMITTEE. Subject to the express
provisions of this 1999 Plan and provided that all actions taken shall be
consistent with the purposes of this 1999 Plan, and subject to ratification by
the Board of Directors only if required by applicable law, the Committee shall
have full and complete authority and the sole discretion to: (i) determine those
persons who shall constitute employees eligible to be Employee Participants;
(ii) select the Participants to whom Stock Options shall be granted under this
1999 Plan; (iii) determine the size and the form of the Stock Options, if any,
to be granted to any Participant; (iv) determine the time or times such Stock
Options shall be granted including the grant of Stock Options in connection with
other awards made, or compensation paid, to the Participant; (v) establish the
terms and conditions upon which such Stock Options may be exercised and/or
transferred, including the exercise of Stock Options in connection with other
awards made, or compensation paid, to the Participant; (vi) make or alter any
restrictions and conditions upon such Stock Options and the Common Stock
received on exercise thereof, including, but not limited to, providing for
limitations on the Participant's right to keep any Common Stock received on
termination of employment; (vii) determine whether the Participant or the
Corporation has achieved any goals or otherwise satisfied any conditions or
requirements that may be imposed on or related to the exercise of Stock Options;
and (viii) adopt such rules and regulations, establish, define and/or interpret
these and any other terms and conditions, and make all determinations (which may
be on a case-by-case basis) deemed necessary or desirable for the administration
of this 1999 Plan. Notwithstanding any provision of this 1999 Plan to the
contrary, only Employee Participants shall be eligible to receive 1999 Plan
ISOs.

      (c) APPLICABLE LAW. This 1999 Plan and all Stock Options shall be governed
by the law of the state in which the Corporation is incorporated.

      SECTION IV. TERMS OF STOCK OPTIONS.

      (a) AGREEMENTS. Stock Options shall be evidenced by a written agreement
between the Corporation and the Participant awarded the Stock Option. This
agreement shall be in such form, and contain such terms and conditions (not
inconsistent with this 1999 Plan) as the Committee may determine. If the Stock
Option described therein is not intended to be an Incentive Stock Option, but
otherwise qualifies as an Incentive Stock Option, the agreement shall include
the following or a similar statement: "This stock option is not intended to be
an Incentive Stock Option, as that term is described in Section 422 of the
Internal Revenue Code of 1986, as amended."

      (b) TERM. Stock Options shall be for such periods as may be determined by
the Committee, provided that in the case of 1999 Plan ISOs, the term of any
such 1999 Plan ISO shall not extend beyond three months after the time the
Participant ceases to be an employee of the Corporation. Notwithstanding the
foregoing, the Committee may provide in a 1999 Plan ISO

                                       18
<PAGE>

that in the event of the Permanent and Total Disability or death of the
Participant, the 1999 Plan ISO may be exercised by the Participant or his estate
(if applicable) for a period of up to one year after the date of such Permanent
and Total Disability or death. In no event may a 1999 Plan ISO be exercisable
(including provisions, if any, for exercise in installments) subsequent to ten
years after the date of grant, or, in the case of 1999 Plan ISOs granted to Ten
Percent Stockholders, more than five years after the date of grant. A Stock
Option granted to a Participant eligible to participate in the Corporation's
Incentive Bonus Program may not be exercisable (including provisions, if any,
for exercise in installments) unless the Fair Market Value of the Common Stock
on the date of exercise exceeds the exercise price of such Stock Option by at
least $2.00.

      (c) PURCHASE PRICE. The purchase price of shares purchased pursuant to any
Stock Option shall be determined by the Committee, and shall be paid by the
Participant or other person permitted to exercise the Stock Option in full upon
exercise, (i) in cash, (ii) by delivery of shares of Common Stock (valued at
their Fair Market Value on the date of such exercise), (iii) any other property
(valued at its Fair Market Value on the date of such exercise), (iv) any
combination of cash, stock and other property, or (v) by way of cashless
exercise and the netting of the number of shares of Common Stock subject to the
Stock Option having an aggregate Fair Market Value equal to the purchase price,
with any payment made pursuant to subparagraphs (ii), (iii), (iv) or (v) only as
permitted by the Committee, in its sole discretion. In no event will the
purchase price of Common Stock be less than the par value of the Common Stock.
Furthermore, the purchase price of Common Stock subject to a 1999 Plan ISO shall
not be less than the Fair Market Value of the Common Stock on the date of the
issuance of the 1999 Plan ISO, provided that in the case of 1999 Plan ISOs
granted to Ten Percent Stockholders, the purchase price shall not be less than
110% of the Fair Market Value of the Common Stock on the date of issuance of the
1999 Plan ISO. The purchase price of shares of Common Stock issuable upon
exercise of any Stock Option may not be changed or amended after a Stock Option
is granted to a Participant.

      (d) FURTHER RESTRICTIONS AS TO INCENTIVE STOCK OPTIONS. To the extent that
the aggregate Fair Market Value of Common Stock with respect to which the
Corporation ISOs (determined without regard to this section) are exercisable for
the first time by any Employee Participant during any calendar year exceeds
$100,000, such Corporation ISOs shall be treated as options which are not
Incentive Stock Options. For the purpose of this limitation, options shall be
taken into account in the order granted, and the Committee may designate that
portion of any Corporation ISO that shall be treated as not an Incentive Stock
Option in the event that the provisions of this paragraph apply to a portion of
any option, unless otherwise required by the Code or regulations of the Internal
Revenue Service. The designation described in the preceding sentence may be made
at such time as the Committee considers appropriate, including after the
issuance of the Stock Option or at the time of its exercise. For the purpose of
this section, Fair Market Value shall be determined as of the time the Stock
Option with respect to such Common Stock is granted.

      (e) RESTRICTIONS. At the discretion of the Committee, the Common Stock
issued pursuant to the Stock Options granted hereunder may be subject to
restrictions on vesting or transferability, provided that all Stock Options
granted hereunder shall be fully vested within 9

                                       19
<PAGE>

years of the date granted. For the purposes of this limitation, Stock Options
shall be taken into account in the order granted.

      (f) WITHHOLDING OF TAXES. Pursuant to applicable federal, state, local or
foreign laws, the Corporation may be required to collect income or other taxes
upon the grant of a Stock Option to, or exercise of a Stock Option by, a holder.
The Corporation may require, as a condition to the exercise of a Stock Option,
or demand, at such other time as it may consider appropriate, that the
Participant pay the Corporation the amount of any taxes which the Corporation
may determine is required to be withheld or collected, and the Participant shall
comply with the requirement or demand of the Corporation. In its discretion, the
Corporation may withhold shares to be received upon exercise of a Stock Option
if it deems this an appropriate method for withholding or collecting taxes.

      (g) SECURITES LAW COMPLIANCE. Upon exercise (or partial exercise) of a
Stock Option, the Participant or other holder of the Stock Option shall make
such representations and furnish such information as may, in the opinion of
counsel for the Corporation, be appropriate to permit the Corporation to issue
or transfer Common Sock in compliance with the provisions of applicable federal
or state securities laws. The Corporation, in its discretion, may postpone the
issuance and delivery of Common Stock upon any exercise of a Stock Option until
completion of such registration or other qualification of such shares under any
federal or state laws, or stock exchange listing, as the Corporation may
consider appropriate. Furthermore, the Corporation is not obligated to register
or qualify the shares of Common Stock to be issued upon exercise of a Stock
Option under federal or state securities laws (or to register or qualify them at
any time thereafter), and it may refuse to issue such shares if, in its sole
discretion, registration or exemption from registration is not practical or
available. The Corporation may require that prior to the issuance or transfer of
shares of Common Stock upon exercise of a Stock Option, the Participant enter
into a written agreement to comply with any restrictions on subsequent
disposition that the Corporation deems necessary or advisable under any
applicable federal and state securities laws. Certificates representing shares
of Common Stock issued hereunder shall bear a legend reflecting such
restrictions.

      (h) RIGHT TO STOCK OPTION. No employee of the Corporation or any other
person shall have any claim or right to be a Participant in this 1999 Plan or to
be granted a Stock Option hereunder. Neither this 1999 Plan nor any action taken
hereunder shall be construed as giving any person any right to be retained in
the employ of the Corporation. Nothing contained hereunder shall be construed as
giving any person any equity or interest of any kind in any assets of the
Corporation or creating a trust of any kind or a fiduciary relationship of any
kind between the Corporation and any such person. As to any claim for any unpaid
amounts under this 1999 Plan, any person having a claim for payments shall be an
unsecured creditor.

      (i) INDEMNITY. Neither the Board of Directors nor the Committee, nor any
members of either, nor any employees of the Corporation or any parent,
subsidiary, or other affiliate, shall be liable for any act, omission,
interpretation, construction or determination made in good faith in connection
with their responsibilities with respect to this 1999 Plan, and the Corporation
hereby agrees to indemnify the members of the Board of Directors, the members of

                                       20
<PAGE>

the Committee, and the employees of the Corporation and its parent or
subsidiaries in respect of any claim, loss, damage, or expense (including
reasonable counsel fees) arising from any such act, omission, interpretation,
construction or determination to the full extent permitted by law.

      (j) PARTICIPATION BY FOREIGNERS. Without amending this 1999 Plan, except
to the extent required by the Code in the case of 1999 Plan ISOs, the Committee
may modify grants made to participants who are foreign nationals or employed
outside the United States so as to recognize differences in local law, tax
policy, or custom.

      SECTION V. AMENDMENT AND TERMINATION: ADJUSTMENTS UPON CHANGES IN STOCK.

         The Board of Directors of the Corporation may at any time, and from
time to time, amend, suspend or terminate this 1999 Plan or any portion thereof,
provided that no amendment shall be made without approval of the Corporation's
stockholders if such approval is necessary under the Code, or rules or
regulations thereunder, or to comply with any applicable rules or regulations of
the Securities and Exchange Commission, including Rule 16b-3 (or any successor
rule thereunder), or the rules and regulations of any exchange or stock market
on which the Corporation's securities are listed or quoted. Except as provided
herein, no amendment, suspension or termination of this 1999 Plan may affect the
rights of a Participant to whom a Stock Option has been granted without such
Participant's consent. The Committee is specifically authorized to convert, in
its discretion, the unexercised portion of any 1999 Plan ISO granted to an
Employee Participant to a Non-qualified Option at any time prior to the
exercise, in full, of such 1999 Plan ISO. If there shall be any change in the
Common Stock or to any Stock Option granted under this 1999 Plan through merger,
consolidation, reorganization, recapitalization, stock dividend, stock split or
other change in the corporate structure of the Corporation, appropriate
adjustments may be made by the Committee (or if the Corporation is not the
surviving corporation in any such transaction, the Board of Directors of the
surviving corporation, or its designee) in the aggregate number and kind of
shares subject to this 1999 Plan, and the number and kind of shares and the
price per share subject to outstanding Stock Options, provided that such
adjustment does not affect the qualification of any 1999 Plan ISO as an
Incentive Stock Option. In connection with the foregoing, the Committee may
issue new Stock Options in exchange for outstanding Stock Options.

      SECTION VI. SHARES OF COMMON STOCK SUBJECT TO THE PLAN.

         The number of shares of Common Stock that may be the subject of awards
under this 1999 Plan shall not exceed an aggregate of 600,000 shares. Shares to
be delivered under this 1999 Plan may be either authorized but unissued shares
of Common Stock or treasury shares. Any shares of Common Stock subject to a
Stock Option hereunder which for any reason terminates, is cancelled or
otherwise expires unexercised, and any shares reacquired by the Corporation due
to restrictions imposed on the shares, shares returned because payment is made
hereunder in shares of Common Stock of equivalent value rather than in cash,
and/or shares reacquired from a recipient for any other reason shall, at such
time, no longer count towards the aggregate number of shares which have been the
subject of Stock Options issued hereunder, and

                                       21
<PAGE>

such number of shares shall be subject to further awards under this 1999 Plan,
provided, first, that the total number of shares then eligible for award under
this 1999 Plan may not exceed the total specified in the first sentence of this
Section VI, and second, that the number of shares subject to further awards
shall not be increased in any way that would cause this 1999 Plan or any Stock
Option to not comply with Rule 16b-3, if applicable to the Corporation.

      SECTION VII. EFFECTIVE DATE AND TERM OF THIS PLAN.

         The effective date of this 1999 Plan is August 13, 1999 (the "Effective
Date") and awards under this 1999 Plan may be made for a period of ten years
commencing on the Effective Date. The period during which a Stock Option may be
exercised may extend beyond that time as provided herein.

         DATE OF APPROVAL BY BOARD OF DIRECTORS:

         DATE OF APPROVAL BY STOCKHOLDERS:

                                       22

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