<PAGE>

                                       1

EXHIBIT 10.15

Consulting Agreement                                          Raytheon

Name of Consultant                                                Date
Dr. John Deutch                                               1 April 1998

Street Address                                      City    State    Zip Code
51 Clifton Street,                                 Belmont,   MA       02178

Raytheon Technical Contact(s)
Robert A. Skelly

You are hereby appointed a consultant to Raytheon Company, (Executive Offices,
Lexington) (hereinafter called "Raytheon") to assist Raytheon in its technical
problems, subject to the following terms and conditions:

1.       Terms of Agreement

The term of this agreement shall be from 1 April 1998 to 31 March 1999 subject
to the right of termination as set forth below.

         You agree to provide, and Raytheon agrees to accept at least 12 days of
service during the first 12 months of this agreement, together with such
additional consulting services as may from time to time be requested in writing
by Raytheon.

2. Statement of Work: (Use additional pages if necessary and attach.)

         Dr. Deutch will consult one day per month and will spend one-half
 day per month on preparatory work.

3.       Payment:

         Raytheon agrees to pay you at the rate of $3,000 per day for each day
worked. Fractional parts of a day shall be prorated on the basis of an eight (8)
hour working day. In addition, Raytheon will pay an annual retainer of
$18,000.00 and $10,000.00 annually for administrative support.

         Check applicable provision

X To the extent authorized, travel expenses including transportation will be
reimbursed at actual costs; provided that such expenses shall not exceed those
allowed for employees of Raytheon.

         No travel expenses are authorized under this agreement.
<PAGE>

                                       2
4.       Submission of Invoices

         You shall keep accurate records of the time expended by you in
performing the services hereunder. Invoices shall be submitted annually for
which services have been requested and performed. Such invoices shall accurately
reflect the dates and number of hours worked, shall identify any other
authorized expenses incurred accompanied by supporting vouchers, and shall make
reference to such agreements.

Applicable Government Contract Numbers

All invoices shall contain the following:

a) "I certify that the above charges are correct and just and that payment
therefore has not been received." b) A written report describing the services
performed.

5.       Standard of Workmanship; Non-Assignment:

         All services hereunder shall be performed in accordance with the
highest professional standards of workmanship. You shall not, in whole or in
part, assign or subcontract any of the services to be performed hereunder
without the prior written consent of Raytheon.

6.       Security:

         The clause set forth in Federal Acquisition Regulation 52.204.2
entitled "Security Requirements," is incorporated by reference herein except
that the term "Contractor" shall mean you and the terms "Contracting Officer"
and "the Government" shall mean Raytheon.

         You agree to keep and maintain an active security clearance
commensurate with the degree of security classification designated by Raytheon
for the work to be performed hereunder.

7.       Compliance with Laws, Regulations and Certifications:

         You agree to comply with all Raytheon policies, rules and regulations
which may be in effect during the term of this agreement, as well as all
Federal, State and Local Laws, Statutes, Ordinances and Regulations.

         You also certify that:

         a. Neither you nor anyone employed by your firm is in violation of
applicable federal statutes such as the Defense Acquisition Improvement Act of
1986, the Post-Employment Restrictions Act of 1988 with regard to the engagement
of former government officers and employees, and Section 423, Title 41 of the
United States code prohibiting certain activities by competing contractors and
Government procurement officials during the conduct of Federal procurements
involving soliciting or discussing post-Government employment, offering or
accepting a gratuity, or soliciting or disclosing proprietary or source
selection information.
<PAGE>

                                       3

b. You have read and understood General Manual "Payments to Government
Officials", No. 10 0003 110; "Principles of Business Ethics and Conduct at
Raytheon," No. 10 007 110; "Observance of Law," No. 900001 110; and "Conflicts
of Interest and Standards of Conduct," No. 90 2001 110.

c. You also certify that the provisions of this paragraph 7 shall be included in
any agreement between you as primary consultant and any second - tier
consultants or subcontractors you engage under this agreement.

8.       Technical Data

         For the purpose of this clause, the term "data" means all information,
including drawings, prints, specifications, reports and designs.

         You agree that all data furnished by Raytheon to you for use in
connection with this subcontract, all data required to be delivered to Raytheon
under this subcontract, and all data arising out of the work called for under
this subcontract shall be and remain the sole property of Raytheon. You further
agree that data shall (1) be kept in confidence and not disclosed to third
parties without the prior written approval of Raytheon, and (2) shall not be
used in the production, manufacture or design of any article or material,
without Raytheon's prior written consent. These obligations shall survive the
termination of this agreement. You shall deliver all data to Raytheon upon
Raytheon's request, and in any event upon the completion or termination of all
work hereunder, whichever first occurs, and you shall be fully responsible for
the care and protection of data until such delivery.

         When assigned a Raytheon Engineering Notebook, the notebook shall
remain the property of Raytheon. You agree to maintain a daily log of all
calculations, sketches and other data relevant to your consultancy in accordance
with the instructions in the Notebook. This Notebook shall be returned to
Raytheon upon termination of this Agreement.

9.       Copyrights and Mask Works:

         You agree that all right, title, and interest in and to all original
works of authorship, including mask works fixed in a semiconductor chip product,
which you produce or compose in conjunction with the services to be performed by
you hereunder for Raytheon or any of its subsidiaries shall belong to Raytheon
and Raytheon shall have the right to obtain registrations of copyright or mask
work thereon throughout the world. To the extent permitted by The Copyright Act
(Title 17, United States Code), all works produced or composed under this
agreement shall be considered works made for hire and belong to Raytheon. You
agree to assign, and do hereby assign, to Raytheon your rights to all other
works of authorship or mask works produced or composed in connection with this
agreement. You further agree to cooperate with Raytheon to secure or protect its
interest in any copyright or mask work relating to this agreement.
<PAGE>

                                       4

10.      Termination and Release

         Raytheon may terminate this agreement at any time upon giving of 60
days written notice to you without further liability to you except for those
services rendered to the effective date of termination and allowable travel
expense hereunder. Prior to and as a condition of final payment, you shall
deliver to Raytheon a release in form and substance satisfactory to Raytheon,
discharging it and the Government, its officers, agents, and employees of all
liabilities, obligations, and claims arising out of this order and the
performance thereof.

11.      Examination of Records:

         You agree that Raytheon Company or, where appropriate, the Comptroller
General of the United States or any of his duly authorized representatives
shall, until the expiration of three years after final payment, under this
agreement, have access to and the right to examine any of your directly
pertinent books, documents, papers, and records involving transactions related
to this agreement.

12.      Covenant Against Contingent Fees

         You warrant that no person or selling agency has been employed or
retained to solicit or secure this agreement upon any understanding that a
commission, percentage, brokerage, or contingent fee will be paid. For breach or
violation of this warranty, Raytheon shall have the right to annul this
agreement without liability, or in its discretion, to deduct from the payments
due, or recover, the full amount of such commission, percentage, brokerage, or
contingent fee.

13.      Patents

         As a part of this agreement, and without additional compensation, you
agree to and do hereby sell, assign, and transfer to Raytheon, its successors
and assignees, the entire right, title and interest in and to any and all
inventions, discoveries, or improvements which are conceived or first actually
reduced to practice in the performance of this agreement, and to all
applications for and Letters Patent covering same, as well as any reissues,
divisions, and extensions of said applications or Letters Patent. You further
agree to furnish Raytheon with complete information on each such invention,
discovery, or improvement and to make, execute and deliver to Raytheon any and
all patents or patent applications, as well as all papers, documents,
affidavits, statements, or other instruments, in such form, terms and contents
as required by Raytheon in or incident to the prosecution of any and all
applications for patent filled by you or Raytheon with respect to such
inventions, discoveries, or improvements or in the adjustment or settlement of
any interferences or other actions or proceedings in which such applications may
become involved.

         Before final payment is made under this agreement, you shall furnish to
Raytheon complete information in respect of inventions, discoveries, or
improvements conceived or actually reduced to practice in connection with the
services performed hereunder; or a statement that no inventions, discoveries, or
improvements emanated from such services. Such information or statement shall be
forwarded to Raytheon's Patent Department, Office of the General Counsel,
Lexington, Massachusetts.
<PAGE>

                                       5

14.      Solicitation Prohibition

         You agree that unless specifically authorized and approved in writing
by Raytheon, you will not solicit, directly or indirectly, the award of any
contract, grant, loan or cooperative agreement to Raytheon from any Raytheon
customer or potential customer.

(INSERT APPROPRIATE UNIVERSITY CLAUSE IF REQUIRED)

Raytheon Company/Authorized Signature                Accepted by Signature
                                                     Date

You are requested to sign and return two (2) copies of this agreement.