Viewing Backgrounds/49297
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Notes:
MOS Si line
Notification:

Date: Wed, 14 Dec 2011 12:56:09 GMT
From: zhangningxiao@gmail.com
To: xmmhelp@sciops.esa.int
Cc: zhangningxiao@gmail.com
Subject: strange Si line

Full_Name: Zhang Ningxiao
Submission from: (NULL) (180.209.6.16)


Dear XMM:

I found a strange Si line when I got the spectra in mos1 from closed
fits(without any source or sky background) download from your website. 

I picked a region on the CCD1,and found there is a Si line in channel 170(maybe
1.7keV). And I picked the same size of the regions in the ccds around ccd1. Then
found there is no or very little Si line in other CCDs.

I am confused because I knew that there is a detector noise line in 1.7keV. But
why only CCD1 have this line?

If you need I can send you my fits later.

Best Wishes

Zhang Ningxiao
Nanjing University,China

Reply 1

From: Matthias Ehle <xmmhelp@sciops.esa.int>
To: zhangningxiao@gmail.com
Subject: Re: strange Si line (PR#49297)
Date: Thu Dec 15 12:29:41 2011

Dear Zhang Ningxiao,

I suggest you to cross-check your findings against what we know about the
EPIC-MOS internal background:

starting at our background working group web page:
http://xmm2.esac.esa.int/external/xmm_sw_cal/background/index.shtml#EPIC
you find a link there to a list of the EPIC background components at
http://www.star.le.ac.uk/%7Eamr30/BG/BGTable.html

If you look under column "internal" in row "spectral" and "spatial structure"
you find links to related papers, esp. I recommend
http://arxiv.org/abs/astro-ph/0204147 which shows in fig. 3 the spatial variance
of the Si fluorescent 
emission.

Regards,
   Matthias

--
   Dr Matthias Ehle 
   XMM-Newton User Support Group
   European Space Astronomy Centre