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                                                            Exhibit 10(d)(vii)


                      AMENDMENT NO. 3 TO EXPORT CREDIT AND
                               SECURITY AGREEMENT

     Amendment No. 3 ("Amendment") dated as of February 28, 2003 to Export
Credit and Security Agreement dated as of November 30, 2000 between AMERICAN
SCIENCE AND ENGINEERING, INC., a Massachusetts corporation ("Borrower") and HSBC
BANK USA, a bank organized under the laws of the State of New York ("Bank").

                              W I T N E S S E T H:

     WHEREAS, Borrower has heretofore entered into financing arrangements with
Bank pursuant to the terms and conditions of an Export Credit and Security
Agreement dated as of November 30, 2000 between Bank and Borrower as amended by
an Amendment No. 1 to Export Credit and Security Agreement dated as of February
14, 2002 between Bank and Borrower and an Amendment No. 2 to Export Credit and
Security Agreement dated November 27, 2002 between Bank and Borrower
(collectively, the "Credit Agreement") and the Financing Agreements (as defined
in the Credit Agreement);

     WHEREAS, Borrower has requested and Bank is willing, subject to the terms
and conditions hereof, to amend the Credit Agreement to extend the termination
date therein.

     NOW, THEREFORE, in consideration of the foregoing premises, the mutual
covenants and agreements contained herein and other good and valuable
consideration, the receipt and sufficiency of which is acknowledged, Borrower
and Bank mutually covenant, warrant and agree as follows:

                            SECTION 1. DEFINITIONS.

     SECTION 1.1. INTERPRETATION. For purposes of this Amendment, unless
otherwise defined herein, all capitalized terms used herein including, but not
limited to, those capitalized terms used and/or defined in the recitals hereto,
shall have the respective meanings assigned to such terms in the Credit
Agreement.

                             SECTION 2. AMENDMENT.

     SECTION 2.1. AMENDMENTS TO SECTION 1.1

     (a) AMENDMENT TO DEFINITION OF EBIT. The definition of "EBIT" contained in
the Credit Agreement is amended by deleting it in its entirety and replacing it
with the following "`EBIT' means total income before interest expenses and
provision for state and federal taxes for any period; PROVIDED, HOWEVER, THAT
the calculation of EBIT for any period shall exclude any expense or income
related to the marking to market effect of the Borrower's issued and outstanding
warrants".

     (b) The definition of "Termination Date" contained in the Credit Agreement
is amended by deleting the reference to "February 28, 2003" and replacing it
with "May 31, 2003".


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                        SECTION 3. CONDITIONS PRECEDENT.

     SECTION 3.1. This Amendment shall only become effective upon the
fulfillment, prior to or contemporaneously with the execution hereof, of the
following conditions precedent:

     (a) EXECUTION OF AMENDMENT. The execution and delivery by Borrower and Bank
of an original of this Amendment;

     (b) PAYMENT OF FEES. (a) The payment by Borrower of: (i) a single amendment
fee to the Bank in the amount of $6,250.00 in connection with this Amendment and
the Amendment No. 3 to Revolving Loan and Security Agreement dated the date
hereof between the Bank and the Borrower; and (ii) legal fees and expenses of
the Bank in the amount of $8,250.00 incurred in connection with the preparation
of this Amendment, and any other documents, instruments or agreements executed
in connection herewith or therewith, including, without limitation, an Amendment
No. 3 to Revolving Loan and Security Agreement, and (b) evidence in form and
substance satisfactory to the Bank that the fees of the Export-Import Bank of
the United States ("Eximbank") required in connection with the extension of the
Eximbank Documents have been paid in full no later than February 28, 2003;

     (c) EXIMBANK ACKNOWLEDGMENT. Receipt by the Bank of a written consent and
acknowledgment of the extension of the Termination Date by the Eximbank and such
other matters as the Bank may deem appropriate; and

     (d) EXECUTION OF RELATED DOCUMENTS AND ADDITIONAL MATTERS. The execution
and delivery by Borrower of an Amendment No. 3 to Revolving Loan and Security
Agreement and a Waiver with respect to the EBIT covenant and all other documents
and legal matters, as may be necessary, in connection with this Amendment and
the transactions contemplated by the Credit Agreement as amended by this
Amendment which shall be reasonably satisfactory in form and substance to Bank.

                           SECTION 4. MISCELLANEOUS.

     SECTION 4.1. REPRESENTATIONS AND WARRANTIES. (a) All terms, conditions,
covenants, representations and warranties (other than any such representation
and warranty that, by its terms, refers to a specific date other than the date
hereof) of Borrower contained in the Credit Agreement, except as expressly
modified hereby, are ratified, confirmed and reaffirmed by Borrower as of the
date hereof, remain in full force and effect as of the date hereof, and are
incorporated herein by reference as if fully set forth herein.

     (b) All terms, conditions, covenants, representations and warranties (other
than any such representation and warranty that, by its terms, refers to a
specific date other than the date hereof; provided, however, that the Schedules
to the Credit Agreement are deemed updated by the information contained in the
Schedules attached hereto) of Borrower contained in all of the other Financing
Agreements, except as expressly modified hereby, are ratified, confirmed and
reaffirmed by Borrower as of the date hereof, remain in full force and effect as
of the date hereof, and are subject to the terms of this Amendment.

     (c) The Borrower represents and warrants to Bank that it has the necessary
power and has taken all necessary action to make this Amendment the valid and
enforceable obligation it purports to be, and that this Amendment constitutes
the legal, valid and binding obligation of Borrower, enforceable against
Borrower in accordance with its terms, except as


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enforcement may be limited by principles of equity, bankruptcy, insolvency, or
other laws affecting the enforcement of creditors' rights generally.

     SECTION 4.2. GOVERNING LAW. THIS AMENDMENT AND THE OTHER FINANCING
AGREEMENTS, AND ALL TRANSACTIONS HEREUNDER, AND ALL THE RIGHTS OF THE PARTIES,
SHALL BE GOVERNED AS TO VALIDITY, CONSTRUCTION, ENFORCEMENT AND IN ALL OTHER
RESPECTS BY THE LAWS OF THE STATE OF NEW YORK. THE BORROWER AGREES THAT THE
COURTS OF THE STATE OF NEW YORK OR THE UNITED STATES DISTRICT COURT FOR THE
UNITED STATES IN THE SOUTHERN DISTRICT OF NEW YORK SHALL HAVE JURISDICTION TO
HEAR AND DETERMINE ANY CLAIMS OR DISPUTES PERTAINING TO THE FINANCING
TRANSACTIONS OF WHICH THIS AMENDMENT IS A PART AND/OR TO ANY MATTER ARISING OR
IN ANY WAY RELATED TO THIS AMENDMENT OR ANY OTHER AGREEMENT BETWEEN THE BANK AND
THE BORROWER EXPRESSLY SUBMITS AND CONSENTS IN ADVANCE TO SUCH JURISDICTION IN
ANY ACTION OR PROCEEDING AND BORROWER WAIVES PERSONAL SERVICE OF PROCESS AND
AGREES THAT A SUMMONS AND COMPLAINT COMMENCING AN ACTION OR PROCEEDING IN ANY
SUCH COURT SHALL BE PROPERLY SERVED AND SHALL CONFER PERSONAL JURISDICTION IF
SERVED BY REGISTERED OR CERTIFIED MAIL TO BORROWER, OR AS OTHERWISE PROVIDED BY
THE LAWS OF NEW YORK STATE OR THE UNITED STATES. NOTHING HEREIN SHALL AFFECT THE
RIGHT OF BANK TO COMMENCE LEGAL PROCEEDINGS OR OTHERWISE PROCEED AGAINST THE
BORROWER EITHER IN ANY OTHER JURISDICTION OR TO SERVE PROCESS IN ANY OTHER
JURISDICTION OR TO SERVE PROCESS IN ANY OTHER MANNER PERMITTED BY APPLICABLE
LAW.

     SECTION 4.3. WAIVERS.

     (a) PREJUDGMENT REMEDY, ETC. THE BORROWER ACKNOWLEDGES THAT THE ADVANCES
ARE COMMERCIAL TRANSACTIONS AND WAIVES ITS RIGHT TO NOTICE AND HEARING ALLOWED
BY ANY STATE OR FEDERAL LAW WITH RESPECT TO ANY PREJUDGMENT REMEDY, AND FURTHER
WAIVES ALL RIGHTS TO REQUEST THE POSTING OF A BOND, WITH OR WITHOUT SURETY, TO
PROTECT THE BORROWER OR ANY ENDORSER, GUARANTOR OR SURETY OF ANY OF THE
OBLIGATIONS AGAINST DAMAGES THAT MAY BE CAUSED BY ANY PREJUDGMENT REMEDY. THE
BORROWER FURTHER WAIVES DILIGENCE, DEMAND, PRESENTMENT FOR PAYMENT, NOTICE OF
NONPAYMENT, PROTEST AND NOTICE OF ANY RENEWALS OR EXTENSIONS.

     (b) JURY WAIVER. THE BORROWER HEREBY WAIVES TRIAL BY JURY IN ANY COURT IN
ANY SUIT, ACTION OR PROCEEDING ON ANY MATTER ARISING IN CONNECTION WITH OR IN
ANY WAY RELATED TO THE FINANCING TRANSACTIONS OF WHICH THIS AMENDMENT IS A PART
AND/OR THE ENFORCEMENT OF ANY OF THE BANK'S RIGHTS, INCLUDING WITHOUT
LIMITATION, TORT CLAIMS.

     (c) VOLUNTARY NATURE OF WAIVERS. THE BORROWER ACKNOWLEDGES THAT IT MAKES
THE FOREGOING WAIVERS IN SUBSECTIONS (a) AND (b) ABOVE, KNOWINGLY, WILLINGLY,
WITHOUT DURESS AND VOLUNTARILY AND ONLY


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AFTER CONSIDERATION OF THE RAMIFICATIONS OF SUCH WAIVERS WITH ITS ATTORNEYS.

     SECTION 4.4. EVENTS OF DEFAULT OR EVENT OF DEFAULT. No Events of Default or
Event of Default has occurred and is continuing on the date hereof or shall be
continuing after giving effect to, or result from, the execution and delivery of
this Amendment and Borrower has no present reason to believe any Events of
Default or Event of Default might or would occur after the date hereof.

     SECTION 4.5. SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All
representations and warranties made in this Amendment or any other documents
furnished in connection with this Amendment shall survive the execution and
delivery of this Amendment and no investigation by the Bank or any closing shall
affect the representations and warranties or the right of the Bank to rely upon
them.

     SECTION 4.6. REFERENCE TO CREDIT AGREEMENT. The Credit Agreement, the
Financing Agreements and any and all other agreements, documents, or instruments
heretofore, now or hereafter executed and delivered pursuant to the terms hereof
or pursuant to the terms of the Credit Agreement, as amended hereby, are hereby
amended so that any reference in the Credit Agreement, the Financing Agreements
or such other agreements, documents or instruments to the Credit Agreement shall
mean a reference to the Credit Agreement as amended hereby.

     SECTION 4.7. FURTHER ASSURANCES. The parties hereto shall execute and
deliver such additional documents and take such additional action as may be
necessary or desirable to effectuate the provisions and purposes of this
Amendment.

     SECTION 4.8. SUCCESSORS AND ASSIGNS. Borrower and Bank as such terms are
used herein shall include the legal representatives, successors and assigns of
those parties.

     SECTION 4.9. COUNTERPARTS. This Amendment may be executed in any number of
counterparts and by the Bank and Borrower on separate counterparts, each of
which when so executed and delivered shall be an original, but all such
counterparts shall together constitute one and the same Amendment.

     SECTION 4.10. SEVERABILITY. Any provision of this Amendment held by a court
of competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

     SECTION 4.11. CONFLICTING PROVISIONS. In the event of any conflict in the
terms and provisions of this Amendment and the terms and provisions of the
Credit Agreement, the terms and provisions of this Amendment shall govern.

     SECTION 4.12. ENTIRE AGREEMENT. This Amendment constitutes the entire
agreement and understanding between the parties hereto with respect to the
transactions contemplated hereby and supersedes all prior negotiations,
understandings, and agreements between such parties with respect to such
transaction.


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     IN WITNESS WHEREOF, this Amendment has been duly executed by the parties
hereto as of the day and year first above written.



                             AMERICAN SCIENCE AND
                             ENGINEERING, INC.



                             By /s/ illegible
                               -------------------------------------------
                               Vice President, General Counsel     (title)
                               and Clerk


                             HSBC BANK USA


                             By /s/ William L. Meli
                               -------------------------------------------
                               William L. Meli                     (title)
                               Vice President