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NeutronDamageofCCDsinATLASEndcap
CamilaPazosBrandeisUniversityJ.Bensinger, K.Hashemi,L.Simpson, R.Studley
RadSimWGMeetingMay21,2019
CCDsintheATLASendcapalignmentsystemcanexperienceabuildupofchargeinpixelsfromthermallygeneratedelectrons,calleddarkcurrent,causedbyneutrondamage.
WemeasurethedarkcurrentintheATLASCCDsandmodeltherelationshipbetweendarkcurrentandneutrondosewiththeequation
I = α D e(T−20°C)/(12°C) counts/px/mswhere,I isdarkcurrentincountsperpixelpermillisecondD istheneutrondosein1012 1-MeVNEcm-2 (Tn)T istemperatureincentigradeα isarateconstantthatdescribesthedarkcurrentgeneratedperneutrondose incounts/px/ms/Tn
Measurementsoftheamountofdarkcurrentinoursystemcouldbeusedasmeasureofneutronflux.
AlignmentSystem&CCDs
BRANDEISUNIVERSITY- CamilaPazos 221-May-19
3
Pre-ProductionExperiments
LowellExperiment:• In1998,fourTC255PCCDheadsweresubjectedtovaryingneutrondoses(between2.0Tnand8.0Tn)over9hourswithaneutronsourceatUniversityofMassachusettsatLowell.
PROSPEROExperiment:• Thefollowingyear,8TC255PCCDheadsweresenttothePROSPEROreactorinFrance.Theyreceivedneutrondosesbetween0.5Tnand10.0Tn.
BRANDEISUNIVERSITY- CamilaPazos
I = 0.28 D e(T−20°C)/(12°C) counts/px/ms
I = 0.26 D e(T−20°C)/(12°C) counts/px/ms
21-May-19
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NeutronDamageinATLAS
DataSetInformation• ImageswerecapturedwitheachCCDandanalyzedtofinddarkcurrentduetoneutrondamage.• Eachdatasetcontainsimagesfrom2670CCDs.• 30datasetscollectedbetween2016- 2018.• RecordtheaveragetemperatureintheATLAScavernforeachdataset.
BRANDEISUNIVERSITY- CamilaPazos
20- 15- 10- 5- 0 5 10 15 20Z (m)10-
5-0
510X (m)
10-
5-05
10
Y (
m)
ATLAS Endcap CCD Map
20- 15- 10- 5- 0 5 10 15 20Z (m)10-
5-0
510X (m)
10-
5-05
10
Y (
m)
ATLAS Endcap CCD Map
21-May-19
5
NeutronDamageinATLAS
• Wemeasuredalldarkcurrent(usingbrightpixels)presentinourCCDsinATLASonOctober16,2018.• ThedarkcurrentdecreaseswithdistancefromIPalongthebeamlineandradiusfromthebeamlineasexpected.
BRANDEISUNIVERSITY- CamilaPazos
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0 2 4 6 8 10 12 14 16 18 20 22 24Distance in Z (m)
0
2
4
6
8
10
12
(m)
2+y2 x
Radi
al D
istan
ce
counts/px/msOct16: Dark current by distance from IP
21-May-19
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NeutronDamageinATLAS- FLUGG
BRANDEISUNIVERSITY- CamilaPazos
4-10
3-10
2-10
1-10
1
10
210
310
410
0 2 4 6 8 10 12 14 16 18 20 22 24 |z| (m)
0
2
4
6
8
10
12
r (m
)
)-1Simulated Neutron Dose (after 154 fb = 14TeVsFLUGG, )-2 1MeVNE cm12(10
0
0.05
0.1
0.15
0.2
0.25
0.3
0 2 4 6 8 10 12 14 16 18 20 22 24 |z| (m)
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r (
m)
a(counts/px/ms/Tn) )-1 Dose (after 154 fb-2 1MeVNE cm12Oct16: Dark Current per 10
C°T = 24 = 14TeVsFLUGG,
= 0.104aavg = 0.247amax
= 0.037amin
http://young.web.cern.ch/young/RadiationMap/
21-May-19
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NeutronDamageinATLAS– GEANT4
BRANDEISUNIVERSITY- CamilaPazos
4-10
3-10
2-10
1-10
1
10
210
310
410
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 |z| (cm)
0
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r (c
m)
)-1Simulated Neutron Dose (after 154 fb = 13TeVsGEANT4, )-2 1MeVNE cm12(10
0
0.1
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0 2 4 6 8 10 12 14 16 18 20 22 24 |z| (m)
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10
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r (
m)
a(counts/px/ms/Tn) )-1 Dose (after 154 fb-2 1MeVNE cm12Oct16: Dark Current per 10
C°T = 24 = 13TeVsGEANT4,
= 0.172aavg = 0.672amax
= 0.049amin
http://radsim.cern.ch/RadiationSimulation/G4_Run2_NIEL_0_1200_0_2400_1_78.txt
21-May-19
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 a
0
5
10
15
20
25
30
35
Num
ber o
f bin
s
value distribution by simluation useda
FLUGG = 0.104aavg
= 0.098amedian
GEANT4 = 0.171aavg
= 0.141amedian
8
α Values- FLUGGvs.GEANT4
BRANDEISUNIVERSITY- CamilaPazos21-May-19
9
NeutronSpectra
BRANDEISUNIVERSITY- CamilaPazos
11-10 10-10 9-10 8-10 7-10 6-10 5-10 4-10 3-10 2-10 1-10 1 10 210 310 410 510 610 [MeV]kin E
310
410
510
610
710
810
910
1010
1110
1210
1310
1410-1/0
.2] @
1 fb
2/M
eV
) [1
/cm
kin
(E
10
/ d
log
Fd
kin Neutron Fluences vs. E = 13TeVsGEANT4,
= 0.672, |z| = 2160cm, r = 310cm a max = 0.049, |z| = 760cm, r = 460cm a min
= 0.141, |z| = 1120cm, r = 750cm a med
11-10 10-10 9-10 8-10 7-10 6-10 5-10 4-10 3-10 2-10 1-10 1 10 210 310 410 510 610 [MeV]kin E
310
410
510
610
710
810
910
1010
1110
1210
1310
1410-1/0
.2] @
1 fb
2/M
eV
) [1
/cm
kin
(E
10
/ d
log
Fd
kin Neutron Fluences vs. E = 13TeVsGEANT4,
closest to IP, |z| = 720cm, r = 200cm = 0.109a
farthest from IP, |z| = 2170cm, r = 1190cm = 0.214a
21-May-19
10
Conclusion
BRANDEISUNIVERSITY- CamilaPazos
• Wemeasureddarkcurrentin2670ATLASendcapCCDs.Usingsimulatedneutronfluxdata,wecalculateddarkcurrentperneutrondosereceived.Wecomparedthesemeasurementstotheresultsobtainedinpast,controlledexperiments:
Experiment α (count/px/ms/dose)
1998Lowell 0.28
1999PROSPERO 0.26
2018 ATLAS- FLUGG 0.104
2018ATLAS– GEANT4 0.172
21-May-19
Backup
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0 2 4 6 8 10 12 14 16 18 20 22 24 |z| (m)
0
2
4
6
8
10
12 r
(m)
a
(counts/px/ms/Tn) )-1 Dose (after 154 fb-2 1MeVNE cm12Oct16: Dark Current per 10
C°T = 24
= 14TeVsFLUGG,
= 0.104aavg = 0.247amax
= 0.037amin
12
NeutronDamageinATLAS- FLUGG
BRANDEISUNIVERSITY- CamilaPazos21-May-19
0
0.1
0.2
0.3
0.4
0.5
0.6
0 2 4 6 8 10 12 14 16 18 20 22 24 |z| (m)
0
2
4
6
8
10
12 r
(m)
a
(counts/px/ms/Tn) )-1 Dose (after 154 fb-2 1MeVNE cm12Oct16: Dark Current per 10
C°T = 24
= 13TeVsGEANT4,
= 0.172aavg = 0.672amax
= 0.049amin
13
NeutronDamageinATLAS– GEANT4
BRANDEISUNIVERSITY- CamilaPazos21-May-19