| Version |
$Revision: 1.4 $ |
| Last Update |
$Date: 2001/11/08 14:46:10 $ |
| HRC CCB Status |
not reviewed |
Number: HRC-R-001
Type: Restriction
Original Date: 1/30/97
Subsystem: HRC
Subject: Lowered MCP HV When Slewing
Source: Informal CARD inputs, e-mail, M. Juda, 9/11/95
CRL Statement:
The Observatory must not slew over bright (200 counts/sec imaged)
X-ray sources if the HRC is at the aim-point and the MCP HV is set to
the operating level.
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. Slews across bright sources must be avoided or,
alternatively, the MCP HV voltage level must be lowered for these
slews.
CRL Impact:
The high counting rates (200 count/sec imaged) generated by bright
sources will permanently degrade HRC MCP performance in regions where
the source is imaged.
Recommended Action:
Incorporate into the Systems and Operations Procedures, with ASC providing
the input, Operations Database, and the OFLS.
$Log: hrc-r-001.html,v $
Revision 1.4 2001/11/08 14:46:10 juda
HTML "href" tag edits to convert to soft links
Revision 1.3 1999/01/20 20:26:19 juda
removed TBSs
Revision 1.2 1998/04/27 13:56:36 juda
Added Version table
modified 1998 March 16
-
Added rate number to Impact section and detail of effect of dose on MCP
gain to Rational/Justification section
Page created 1998 March 4 - Based on 30 Jan 98 release of OP05
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