Transcript スライド 1

XIS Calibration Report
2006 Feb 22
(revised 2006 Feb23)
K. Hayashida (Osaka Univ.) and
the SUZAKU XIS team
Menu
• Minimum Notes on XIS data processing
• Gain/CTI
– Charge Trail Correction
– CTI Correction /Charge Injection
– Ex-PHA Relation / Response
• QE degradation
– RXJ1856,E0102,Cyg Loop, Earth Atmosphere
– Modeling
• Background Study and Data Base
– COR, PINUD dependence
– Data Base and Subtraction method
• Data Selection Criteria
• Bad Columns / Hot Pixels
XIS Data Reduction
PHAS(6)
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Dark-level Subtraction
Event Pickup (PHAS(0)>Event Threshold)
5x5 mode, 3x3 mode or 2x2 mode
Event data
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Charge Trail Correction
CTI correction
Grading / PHA-reproduction for PHAS(i)>Split
Threshold
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PHAS(0)
Frame Data /8sec
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On the ground
Onboard DE
XIS Response depends on the reduction procedure
PHAS(7)
PHA-dependent Split Threshold for BI
EHK screening
Bad Columns Filter
xisclean
XIS cleaned event list
Darklevel Estimation and Subtraction
• Dark-level of each Pixel “Dark” is determined onboard
after every SAA passage in DarkInit / DarkUpdate DEmode.
• DE also calculate the Darklevel shift with time for each
frame (8sec) for each (e.g. 64x64pixels) partition. We
call it “LightLeak” value.
– One LightLeak value for one partition
• Pixel-Level “PHAS[]” = Raw-Pixel-Level – “Dark” –
“LightLeak”(of the Previous Frame)
• “LightLeak ” value shifts slowly in time.
• Only when bright Earth come into the FOV, “LightLeak ”
increases dramatically. It makes error in pixel levels, and
thus in PHA and in event number.
• *) D LLL(=increment of the LL from previous frame to the
current frame) can be an indicator of such effect.
• *) “LightLeak written in the XIS data products is in 1/8
ADU unit.
Event Grades

Grades 02346 are
used as X-ray
events.
Pixel level is maximum among 3x3 area
and larger than Event threshold
Pixel level is larger than Split threshold
and added to the PHA
Pixel level is larger than Split
threshold but NOT added to the PHA
grade0
grade4
grade1
grade5
grade2
grade6
grade3
grade7
Charge Trailing
２
０
０ Grade0
events
Vertical
２
０
０ Grade2
００
０
１０００ ０
５００
ACTY
５００
ACTY
１０００
PH
Some charge is deposited in trailing pixels
transfer
Grade0
transfer
Trailing charge
transfer
Grade2
Charge Trail
ＰＨ（２）= preceding pixel ，ＰＨ（７）=trailing pixel
RAWY
BI1 5.9keV X-ray incidence
a
b
Near
readout
node
d
c
b
PH [ADU]
PH [ADU]
a
c
PH [ADU]
Far from
readout
node
d
PH [ADU]
PHAS(2),PHAS(7) Distribution before/after Charge Trail Correction
PH [ADU]
PHAS
[ADU]
PH
[ADU]
PHAS
[ADU]
PH [ADU]
PHAS
[ADU]
PH [ADU]
PHAS
[ADU]
Charge Trail Correction
Grade02346 event distribution
３
０
０
couns
counts
３
０
０
not uniform!
Berore Correction
０
０
５００
ACTY
１０００
After Correction
０
５００
ACTY
０
Save grade7 events
Correction saves 10—20% of event at high energy
１０００
Calibration Source
Window
55Fe
Door
Hinge
Door Close
Calibration
source
Bonnet
Calibration source
Optical blocking filter
CCD
(imaging region)
Doors cannot be closed again
Door Open
Determination CTI parameters included in rev0.6 data (H. Yamaguchi)
Q’ = Q(1-CTI)N
→ CTI = (Q- Q’) / Q / N
Q = PHA(ACTY=0)
Q : Initial charge
Q’ : Readout charge
N : Number of P transfer
CTI =
PHA(Y=0) – PHA (Y=896, T)
PHA(Y=0)×896
CTI(Seg1) = CTI(Seg 2)
= [CTI(Seg0) + CTI(Seg3)] / 2
Whole Area cal src data (8/11)
Corner cal src data
(8/15～11/20)
CTI = CTI_CONST
+ CTI_NORM×(PHAS)CTI_POW
In rev0.6…
CTI_POW = -0.5
CTI_CONST = 0
Q’(T) = PHA(ACTY=896, T)
T
CTI correction in rev0.6
• Determine CTI_NORM for each quadrant
– Column by Column difference is not taken into account.
• Fit CTI_NORM as a function of time with a straight line.
• Make a CALDB table which has columns, time,
CTI_NORM, CTI_CNST etc. One row per a week.
• Fill (modeled) CTI_NORM.
• Correction is done with a critical ftool “xispi” to PHAS[],
after Charge trail correction but in prior to event grading.
– Corrected PHAS[] is not written in XIS event file.
– In principle, gain shift by CTI is corrected in xispi (data reduction)
not in response.
• Line broadening is inevitable even with CTI correction.
(Charge Injection data helps the broadening partially).
The effect must be taken into account the response but
not yet.
– Response builder for that has almost prepared.
Results of CTI correction
Mn-Kα
5.84keV (rev0.3)
→ 5.88keV (rev0.6)
@2006/01
Cal src (rev0.6)
by Nakajima
OVIII line
0.654keV
Cygnus Loop (rev0.6)
by Katsuda
CTI parameters should be improved.
(CI data were obtained on 2006/01.)
Residual error in CTI Correction of rev0.6
• Simplified Assumptions:
– CTI (ACTY=0,t)=CTI(ACTY=0,t0=2005Aug)
• There must be degradation in CTI Imaging to Frame Store Area
Transfer
– CTI is proportional to Ex-0.5
• Need to be checked its accuracy with orbital data.
• Mn-Ka peak ch history was made with G02346
– CTI correction is for each pixel PHAS[], G0 data should be
employed.
• We need to check the energy scale in rev0.6 data with
various t, Ex, ACTY, (ACTX)
– Feedback from SWG members will be acknowledged. Expected
Energy is sometimes uncertain. Need detailed knowledge for
each source, too.
– (for XIS team) Ni-K line, Al-K etc in BGD might be useful, though
its not certain they are imaging area event.
• NOTE: If Charge-Trail correction parameters mismatch,
not only energy scale but also (effective) QE is affected.
Revision of Ex-PHA Relation: XIS2 Segment 0
Old: Single linear function fit: 2 parameter model
(caldb=ae_detgain_20050703.ext)
New: 2 linear functions for E<Esik and E>Esik:
4 parameter model
(caldb=ae_xi2_makepi_2040822.fits)
Si K edge (E=1839 eV)
In this case, the systematic offset of ~4ch (~15eV) in the
soft X-ray region is largely reduced.
PKS2155 (rev0.3) residuals
Structure around Si-Kedge is mainly due to broken line
approximation of the Ex-PHA relation.
Should update Ex-PHA relation (PHA-PI conversion) in
xispi
RXJ1856.5-3754
Discovered with ROSAT
 Nearby (D~120pc) Isolated Neutron Star
 X-ray spectrum is fitted with a simple
blackbody ( against NS atmosphere model).
 R~4-5km Quark Star ?
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Rev0.3 data -10eV offset
Suzaku Obs 2005-10-24~10-26
RMF 20051210 a-d for XIS1
a: Based Cal on the Ground
b: a x excess0.15mmC
c: Dead Layer =Design Value
d: c x excess0.15mmC
Calibration Task Share
Components
Location
X-ray Source
QE reference
Chip level
CSR/MIT
Fluorescent X-rays
(C,O,F,Al,Si,P,Ti,Mn,Cu)
ACIS chips
calibrated at
BESSY
Camera
without OBF
+FM AE
Osaka
Grating Spectrometer
0.2-2.2keV
Polypro-window
Gas PC & XISEU
Kyoto
Fluorescent X-rays
(Al,Cl,Ti,Mn,Fe,Zn,Se)
Window-less
SSD
OBF
Synchrotron Synchrotron X-rays +
Facility
monochrometer
Camera
onboard the
satellite
ISAS/JAXA
55Fe
(Transmission
measurement
with PIN diode)
-1deg offset slant-PC is assumed
QE(PC)->QE(EU)->XIS BI1 QE
Best Fit
Estimates
BI1_absQE
Some data points exceeds 1
1
Difficult to reproduce 0.28keV QE
with simple absorption models.
QE(Osaka)
QE(Kyoto)
QE(MIT)
BI1 QEmodel with H2O
BI1 QEmoel without H2O
BI1-QE-model lowecut
0.1
1
10
Ex(keV)
HfO2
0.005mm fixed
Ag
0.001mm fixed
SiO2
0.000±0.0005m
m
Si
depletion
43.6±0.7mm
Constant 0.961±0.003
Factor
At low energy side,
artificial cutoff in the form
of erf(Ex) is introduced.
This model QE is used as
a new reference.
Rev0.6 data (with no gain shift)
Wabs x BBodyrad x Varabs
kT  63.5eV ( fixed )
N H  0.95  1020 / cm 2 ( fixed )
N C  1.49  0.04  1018 / cm 2
N N  0.00  0.09  1018 / cm 2
N O  0.00  0.14  1018 / cm 2
O/C <10%
Suzaku/XIS Contamination
Measurements with E0102
• E0102: SNR in SMC, bright in soft X-ray lines
• excellent calibrator for low-E gain, QE changes
• contamination degrading low-E eff. area of all XIS’s
• model
• thermal bremss + 24
Gaussian emission lines
• Galactic + SMC absorption
• pure C absorption from
contaminant (varabs)
• gain shift -5 eV ~ -15 ev
• r2 ~ 1.6 (FIs) to 2.5 (BI)
OVIII
NeIX
NeX
MgXI
OVII
2005-08-13
2005-08-31
2005-12-16
2006-01-17
2006-02-02
XIS Contamination Rate
• empirical correction for observers
• contamination rate turnover (?)
• SMC NH uncertainty  systematic error ±0.02 mm independent of
epoch
change in effective C column:
chip
XIS0
XIS1
XIS2
XIS3
slope
intercept
(1016 cm-2/day)
1.6 ±0.1 4.4 ±4.0
2.7 ±0.1 -9.6 ±15
3.1 ±0.1 -3.2 ±14
4.1 ±0.5 54. ±50.
Count Rate History
Count Rate History
Count Rate History
From Anabuki et al.’s poster
Atmospheric N-K line Map XIS1(BI)
Color code is adjusted for each map
2005-8-13
2005-9-4
2005-10-22
2005-11-28
2005-12-24
2006-2-6
N-K line
Day Earth
0 < DYE_ELV < 5
5 < DYE_ELV < 10
10 < DYE_ELV < 15
15 < DYE_ELV < 20
20 < DYE_ELV < 25
Atmospheric O-K line Map XIS1(BI)
2005-8-13
2005-9-4
2005-10-22
2005-11-28
2005-12-24
2006-2-6
Day Earth
0 < DYE_ELV < 5
5 < DYE_ELV < 10
10 < DYE_ELV < 15
15 < DYE_ELV < 20
20 < DYE_ELV < 25
Day Earth Radial Profile
(vignetting corrected,normalized by center region)
E0102-72
N-K line
O-K line
A2811_offset
N-K line
O-K line
SN1006_NE_BGD
Mrk 3
N-K line
O-K line
N-K line
O-K line
NGC 4388
MBM12_off Cloud
N-K line
O-K line
N-K line
O-K line
Center 6mm radius / Other area
N-K
line
O-K
line
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Mean Free Path in
C(2.2g/cc)
0.182mm for N-K
line
0.375mm for O-K
line
•Spatial Difference in Carbon contamination thickness can be
modeled with Atmospheric N-K, O-K data.
•Thickness at the center is evaluated by E0102 and RXJ1856
obs.
•Thickness (t,detx,dety) will be modeled/introduced in arfbuilder
(or rmfbuilder).
[Central 6mm radius count rate] / [Outer area count rate]
N-K line
O-K line
c.r.(center) - c.r.(outer)=0.9x10-3 mm/day
c.r.(center)~ 2.5x10-3 mm/day
c.r.(outer)=1.6x10-3 mm/day
Time(sec)
Bad (CTE) Columns
X-ray image
(number of
events /pixel)
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Bad CTE
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Identification logic without accumulating
10^7events was developed.
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Typically long trail in each event.
Sometimes flickering pixel is observed.
Rows near the readout node can be used.
EU= 21 bad columns/chip
XIS0=14, XIS1=50, XIS2=17,XIS3=24
How should we do for adjacent columns ?
Calibration Status and Plan
• QE degradation are going to be modeled as a function of
time and distance from the FOV center.E0102, RXJ1856,
DarkEarth. => arf-builder or emfbuilder.
– QE at C-K line on the ground is ½ of the orbital QE?
• CTI correction was introduced in rev0.6 processing.
Need to be checked in various sources. (Energy, time,
position dependence) Feedback from SWG is expected.
• PHA->PI conversion (xispi) should be upgraded.
• Charge Trail Correction (introduced from rev0.3)
parameters should be checked with 2006 data.
• Resolution decrease (inevitable with CTI correction)
should be included in the response. rmf-builder can do it.
CI measurement and CTI correction by each column
might be used to save the degradation
• Background data base is under construction. Bad
Columns data base should be updated.
• Data-Selection Criteria will be revised from (ELV>5 &&
DYE_ELV>20) to (ELV>5).