| Version |
$Revision: 1.4 $ |
| Last Update |
$Date: 2001/11/08 14:46:10 $ |
| HRC CCB Status |
not reviewed |
Number: HRC-R-004
Type: Restriction
Original Date: 1998 March 18
Subsystem: HRC
Subject: Minimum dither frequency with HRC at aim-point
Source:
CRL Statement:
The frequency of the dither pattern should not be set lower than 0.36 deg/sec
(0.001 Hz) when the HRC is at the aim-point of the HRMA.
CRL Rationale/Justification:
The HRC sensitivity to bright objects is derived from the HRC design.
A localized region on the HRC MCPs that receives a dose of more than 500
events per MCP channel undergoes a permanent reduction in gain of 10%;
increasing dose above this leads to further reduction in gain. Dithering
too slowly can allow an on-axis, imaged x-ray source to produce to high
a localized dose.
CRL Impact:
The event dose from a too slowly dithered source can produce a localized
permanent degradation in the HRC MCP gain.
Recommended Action:
Incorporate into the Systems and Operations Procedures, with ASC providing
the inputs, and Operations Database.
$Log: hrc-r-005.html,v $
Revision 1.4 2001/11/08 14:46:10 juda
HTML "href" tag edits to convert to soft links
Revision 1.3 1998/06/17 16:26:10 juda
Updated restriction number to agree with TRW CARD (HRC-R-005? replaced with HRC-R-004)
Revision 1.2 1998/04/27 14:00:17 juda
Added Version table
Page created 1998 March 18
Dr. Michael
Juda
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Mail Stop 70
Cambridge, MA 02138, USA
Ph.: (617) 495-7062
Fax: (617) 495-7356
E-mail: mjuda@cfa.harvard.edu