LHCb Silicon Detectors: The Run 1 to Run 2 transition ......MPV Module Number: 36, R: All-1 = 0.04...
Transcript of LHCb Silicon Detectors: The Run 1 to Run 2 transition ......MPV Module Number: 36, R: All-1 = 0.04...
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LHCb Silicon Detectors:The Run 1 to Run 2 transition
&First Experience of Run 2
Kurt Rinnert
On behalf of the LHCb VELO & ST Groups
VERTEX 2015Santa Fe, 1 – 5 June 2015
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The LHCb Detector
More on tracking in Stefano’s talk (up next)
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 1 /28
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The Vertex Locator (VELO)
Retractable detector halves21 R/Phi modules per half+4 R-type PU veto2048 strips on each sensorPitch varies from 40 μm to100 μmBest hit resolution 4 μmFirst strip at 8.2 mmOperates in secondaryvacuumBi-phase CO2 cooling,Si at -10 ◦CSeparated from beam vacuumby 300 μm thick Al foil
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 2 /28
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The Tracker Turicencis (TT)
~30 cm
TTb
TTa
zy
x
132.
4 cm
157.2 cm
132.
4 cm
138.6 cm7.
4 cm
7.74 cm
Silicon microstrip sensors,p-on-n by HPKThickness 500 μmStrip Pitch 183 μmReadout strip lengthup to 37 cm ⇒ up to 60 pF∼144k readout channelsTotal area: 8 m2
Sensors at ∼ 8◦ C99.7% working channels(Run I average)Resolution 53.4 μm
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 3 /28
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The Inner Tracker (IT)
21.8
cm
41.4
cm
125.6 cm
19.8 cm
Silicon microstrip sensors,p-on-n by HPKTwelve layersThickness 320 μm (1 sensor,11 cm) or 410 μm (2 sensors22 cm)Strip Pitch 198 μm∼130k readout channelsstereo angles ()0◦,−5◦,+5◦,0◦,Total area: 4.2 m2
Sensors ar ∼ 8◦ C98.6% working channels(Run I average)Resolution 54.9 μm
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 4 /28
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Evaluation of Radiation Damage
Methods with and without beam:
Current vs. temperature (IT)Changes of current vs. voltage (IV)Changes of effective depletion voltageCluster finding efficiency
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 5 /28
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Leakage Current (VELO)
Two contributions: bulk and surface currentSurface contribution negligible after irradiation
Bulk dominated beforeBulk dominated after
Surface dominated beforeBulk dominated after
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 6 /28
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Leakage Current (VELO)
Measurement of the effective bandgap energy.(T) ∝ T2ep(−Eg2kT )
Bulk dominated beforeBulk dominated after
Luminosity EgVoltage[fb−1] [eV][V]0.48 1.17 ± 0.07 ± 0.041000.48 1.18 ± 0.05 ± 0.041500.82 1.14 ± 0.06 ± 0.041501.20 1.15 ± 0.04 ± 0.04150
Literature: Eg = 1.21 eVLHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 7 /28
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Leakage Current (VELO)
IV-scans performed weekly in data taking periodsBulk currents increase with fluence as expectedOccassional drops due to annealing
Sep2010
Feb2011
Apr2011
Jun2011
Aug2011
Oct2011
Dec2011
Feb2012
Apr2012
Jun2012
Aug2012
Oct2012
Dec2012
Feb2013
Cu
rren
ts [
mA
]
0
0.02
0.04
0.06
0.08 Individual Sensors
Mean - Measured
Mean - Predicted
LHCb VELO
]
-1 [
pb
int
L
2000
4000
6000
Delivered Luminosity
C]
oT
[
-20
0
20 Sensor Temperatures
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 8 /28
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Leakage Current (TT + IT)
Data normalised to a temperature of 8◦C (Eg = 1.21 eV)
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 9 /28
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Predicted Fluence (VELO)
Good agreement with predictionParticle fluences well understood
z [mm]0 500
% e
rror
0
0.5
1
1.5
2
2.5
3
3.5
4
z [mm]0 500
21
MeV
neu
tron
s cm
0
10
20
30
40
50
60
701210!
z [mm]0 500
% e
rror
0
0.05
0.1
0.15
0.2
0.25
z [mm]0 500
Cur
rent
[mA
]
0
0.02
0.04
0.06
0.08
0.1A Side PredictionC Side PredictionA Side R sensors
sensors"A Side C Side R sensors
sensors"C side
LHCb VELO!
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 10 /28
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Charge Collection Efficiency (VELO)
Use reconstructed unbiased tracksExtrapolate to test sensor and record nearby chargeVary voltage between 40 and 250 V
Same concept for ST, scans are simultaneous.
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 11 /28
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Charge Collection Efficiency (VELO)
Collect data for various bias voltages for each sensorFit the MPV distributionDefine effective depletion voltage (VED) as the voltagewhere MPV is 80% of maximum
ADC Counts-20 0 20 40 60 80
Rel
ativ
e n
um
ber
of
trac
ks
Charge_S36_V10_R_all
Bias voltage:
10V40V
70V
-1 = 0 pbL
LHCb VELO-1 = 0.04 fbL
Rel
ativ
e n
um
ber
of
trac
ks
Bias voltage [ V ]0 20 40 60 80 100 120 140 160
MP
V o
f AD
C C
ou
nt
Dis
trib
uti
on
0
5
10
15
20
25
30
35
40
LHCb VELO
R-type sensor
-type sensorφ
MPV Module Number: 36, R: All
-1 = 0.04 fbL
Same concept for ST, scans are simultaneous.
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 12 /28
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VED Dependency on Fluence (VELO)
VED decreases with fluence to a minimum of ∼18 V forn-type sensorsInversion point is 10 − 15 × 1012neqcm−2After inversion n-in-n increase at a similar rate as n-in-p
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 13 /28
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Comparison with Hamburg Model
Good agreement apart from inversion regionNo inversion observed for ST
VELO
fluenceeq1 MeV n1010 1110 1210 1310
Eff
ecti
ve D
eple
tio
n V
olt
age
[ V
]
10
20
30
40
50
60
70
80
Initial EDV:55 - 65 V45 - 55 V25 - 35 VHamburg model
Initial EDV:55 - 65 V45 - 55 V25 - 35 VHamburg model
LHCb VELO preliminary
ST
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 14 /28
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VELO VED Predictions for Run 2
Sensor VED at 4.4 fb−1 [V] VED at 10 fb−1 [V]
R 172 ± 12 432 ± 30ϕ 164 ± 11 404 ± 26
VED will no longer be uniform across sensorsDifferent voltage steps in CCE scansWell below 500 V in worst case
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 15 /28
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Second Metal Layer (VELO)
CFE depends on distance to routing linesEffect seems to reduce after type inversionNo effect on track finding efficiency observed
Y [mm]-50 -40 -30 -20 -10 0 10 20 30 40 50
X [m
m]
-10
0
10
20
30
40
50
CF
E [%
]86
88
90
92
94
96
98
100
LHCb VELO preliminary-1 = 3.4 fbL
m ]µRL distance [
Clu
ster
Fin
ding
Effi
cien
cy [
% ]
88
90
92
94
96
98
100
0 4 8 12 16 20 24 28 32 36 40 ~ 2000
d = distance to edge of nearest strip
m) < 0µd(m) < 5µ0 < d(m) < 10µ5 < d(
m) < 15µ10 < d(m) < 20µ15 < d(
LHCb VELO preliminary-1 = 3.4 fbL
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 16 /28
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Maintenance during LS 1
The detectors have been kept cooled and monitored.Regular scheduled operations to ensure all is well.The VELO LV system has been refurbished.The IT adjusted to nominal position and a new alignmentmonitoring system has been installed.Maintenance of VELO cooling & vacuum system and newcooling plant for ST.Some challenging times with the VELO under Ne and nobeam pipe attached.PVSS is now called WinCC/OA – manychanges/improvements to control infrastructure.
And more. . .
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 17 /28
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New ST Cooling Plant
Cooling performace degraded over Run1, due to lubricantcontaminating coolant.Manual recirculating necessary ervery 2-3 days.New Cooling plant installed for Run 2; better insulationneeded.
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 18 /28
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IT Postion
After installation of new beam pipe IT could be moved toits nominal position.New position monitoring system installed (BCAM).
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 19 /28
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VELO Maintenance Examples
VELO under Ne w/o beampiperequired installing mechanicalsupport.Replaced LV bulk supplieswith A3485 units to mitigateconnector problems.VELO 2 (emergency spare)moved back upstairs.
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 20 /28
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Preparational Data Taking
TED
Shots on transfer linebeam absorber.Results in muon showersat LHCb in the upstreamdirection.Many parallel tracks,unlike collissions.Special timing settings.
SMOG
Injection of Ne in theprimary LHC vacuum atLHCb.Was done simultaneouslywith injection energy (450GeV) collissions.No stable beams declared,so VELO was open.Allowed to power becausebeams were “quiet”.
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 21 /28
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TED: IT Track Residuals
IT Top IT A-Side
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 22 /28
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TED: VELO Alignment
Translation along x
z [m m ]200− 0 200 400 600
m]
µ[x
T
10−
8−
6−
4−
2−
0
2
4
6
8
10TE D 14
2012
xR -sensors T
LHCb preliminary
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 23 /28
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SMOG: IT CLuster Distributions
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 24 /28
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SMOG: VELO Beam Monitor
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 25 /28
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Summary
The LHCb silicon detectors have been maintained &monitored well during LS1.Radiation damage is well understood.Many improvements have been put in place over LS1.The detectors performed well during injection line testsand first collision runs.We will be recording data with stable beams this week!
VELO & ST are in good shape and ready for LHC Run 2
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 26 /28
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Summary
The LHCb silicon detectors have been maintained &monitored well during LS1.Radiation damage is well understood.Many improvements have been put in place over LS1.The detectors performed well during injection line testsand first collision runs.We will be recording data with stable beams this week!
VELO & ST are in good shape and ready for LHC Run 2
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 27 /28
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References
PerformanceInt. J. Mod. Phys. A 30 (2015) 1530022J. Instrum. 9 (2014) P09007Radiation DamageJINST 8 (2013) P08002
LHCb VELO & ST — VERTEX 2015 — Santa Fe, 1 – 5 June 2015 28 /28
http://arxiv.org/pdf/1412.6352.pdfhttp://arxiv.org/pdf/1405.7808.pdfhttp://arxiv.org/abs/arXiv:1302.5259