**Exhibit 31.2**

**CERTIFICATION OF CHIEF FINANCIAL OFFICER**

**Section 302Certification**

I, Kenneth J. Galaznik,certify that:

1.               Ihave reviewed this quarterly report on Form 10-Q of American Science andEngineering, Inc.;

2.               Basedon my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;

3.               Basedon my knowledge, the financial statements, and other financial informationincluded in this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, andfor, the periods presented in this report;

4.               Theregistrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange ActRules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act rules 13a-15(f) and 15d-15(f))for the registrant and have:

a)              Designed such disclosurecontrols and procedures, or caused such disclosure controls and procedures tobe designed under our supervision to ensure that material information relatingto the registrant, including its consolidated subsidiary, is made known to usby others within those entities, particularly during the period in which thisreport is being prepared;

b)             Designed such internal controlover financial reporting, or caused such internal control over financialreporting to be designed under our supervision, to provide reasonable assuranceregarding the reliability of financial reporting and the preparation offinancial statements for external purposes in accordance with generallyaccepted accounting principles;

c)              Evaluatedthe effectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period covered by thisreport based on such evaluation; and

d)             Disclosed in this reportany change in the registrant’s internal control over financial reporting thatoccurred during the registrant’s most recent fiscal quarter that has materiallyaffected, or is reasonably likely to materially affect, the registrant’sinternal control over financial reporting;

5.                Theregistrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to theregistrant’s auditors and the audit committee of the registrant’s board ofdirectors (or persons performing the equivalent functions):

a)              All significantdeficiencies and material weaknesses in the design or operation of internalcontrol over financial reporting which are reasonable likely to adverselyaffect the registrant’s ability to record, process, summarize and reportfinancial information; and

b)               Anyfraud, whether or not material, that involves management or other employees whohave a significant role in the registrant’s internal control over financialreporting.
| Date: August 9, 2007 |   | /s/ Kenneth J. Galaznik          |
|---------------------------|--------|---------------------------------------|
|                      |   | Kenneth J. Galaznik                   |
|                      |   | Chief Financial Officer and Treasurer |

 

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