LXe Beam Test Result
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Transcript of LXe Beam Test Result
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LXe Beam Test ResultCEX beam test 2004
Cryogenic Equipment Preparation Status
Liquid Xenon Photon Detector Group
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Charge Exchange Beam Test at piE5
New PMTs R9288TB higher QE and better performance under high BG Resolutions to be improved
New calibration alpha sources New refrigerator with higher cooling power TEST at piE5 beam line
Gain experience Analysis framework
ROME in online (offline also) analyses Waveform data obtained with DRS prototype
boards
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1st generation R6041Q 2nd generation R9288TB 3rd generation R9288ZA
228 in the LP (2003 CEX and TERAS)
127 in the LP (2004 CEX)
111 In the LP (2004 CEX) Not used yet in the LP
Rb-Sc-Sb
Mn layer to keep surface resistance at low temp.
K-Sc-Sb
Al strip to fit with the dynode pattern to keep surface resistance at low temp.
K-Sc-Sb
Al strip density is doubled.
4% loss of the effective area.
1st compact version
QE~4-6%
Under high rate background,
PMT output reduced by 10
-20% with a time constant of
order of 10min.
Higher QE ~12-14%
Good performance in high rate BG
Still slight reduction of output in very high BG
Higher QE~12-14%
Much better performance in very high BG
PMT Development Summary
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Alpha sources on wires
4 tungsten wires plated with Au (50 micron )
Po attached on the wires, 2 active points per wire
~40Bq per point on 2 wires at the rear side
~130Bq per point on 2 wires at the front side
Active points are coated with Au (200-400Å)
Fixed on the wall with spring. Alpha sources on the walls were
removed
gamma
wire
LED
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New Refrigerator (PC150W)
MEG 1st spin-off Technology transferred to a
manufacturer, Iwatani Co. Ltd
Performance obtained at Iwatani
189 W @165K 6.7 kW compressor 4 Hz operation
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CEX Elementary process -p0n
0(28MeV/c) MeV
eV
• Requiring
FWHM = 1.3 MeV
• Requiring > 175o
FWHM = 0.3 MeV
170o
175o
0
54.9MeV 82.9MeV
1.3MeV for >170o
0.3MeV for >175o
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Beam Test Setup
H2 target+degrader
beam
LPNaI
LYSO
Eff ~14%
S1Eff(S1xLP)~88%
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Beam Condition Profile at the target (with a pill
counter) Vertical 13.2mm Horizontal 9.9mm
Pion rates (w/o separator) 1.8mA and 4cm Target E.
Slits 80: 2.07 x108 п -/sec Slits 100: 3.95 x108 п - /sec
Profile at S1, 2mm/bin
Optimization of degrader thickness20mm + 3.3mm x n
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Operation Status
Thanks to a new refrigerator we succeeded to operate the detector (almost) without using LN2 except for power break and recovery.
New pressure reducer also helped this while pre-cooling and liquefaction.
Circulation/purification continued during DAQ. History
September• 18~21 Pre-cooling (72 hrs)• 21~24 Liquefaction (79 hrs)• 24 Circulation start (~30 cc/min)• 24 Electronics setup
October DAQ started 25 DRS boards installed 29 Recovery of xenon
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Data set
Gain ADC gate Beam intensity event# *
High
400 nsec
Low -
middle 32 + 29** k
high -
600 nseclow -
middle 48 k
high -
Normal
400 nsec
low 55 k
middle 110 + 44** k
high -
600 nsec
low 77 k
middle 85 k
high 47 k
And Waveform data…
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Analysis Result
CalibrationEnergy Timing
1st look on waveform Data
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Alpha data
One of the rear wires found to be slipped Weighted position average surround wires
due to shadow effect. Reconstructed Position is far from wires
Wire (50 μm ϕ)
Alpha
40 μm Po half-life=138 days
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The two wires on the front face are a little displaced
LXe GXe
Source Position Reconstruction
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Alpha data analysis
Nphe[0]
Nphe[0] for top-left alpha
Center of the PMT-0
with alpha emission angle selection
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LXe/MC, absorption length evaluation
Applying the QEs determined in GXe (-75˚C)
4 front sources
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Q.E. evaluation with alpha events in liquid
R9288
R6041
Data #8528 normal gain front 4 alphas
MC reflection on quartz on no absorption scattering length :45cm for 175 nm
Q.E. evaluation using alpha data in the liquid is also possible.
Higher light yield Expected better evaluation if xenon is pure!
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Energy Reconstruction
Cut-based Qsum Analysis
Linear Fit Analysis
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Cut-based Qsum analysisEvent Selection
83 MeV to Xe83 MeV to Xe
55 MeV to Xe55 MeV to Xe
Cut-based Qsum analysis
MCMC
Exe
non[
n ph]
Analyze only central events to compare with the previous result
|Xrec|, |Yrec|<2cm 70 MeV < ENaI+ELYSO < 105MeV Sigma2 > 40 (discard events if shallow)
Sigma2: broadness of the event measured by using front face PMTs depth parameter
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Correction and selection efficiency
Before depth correction
After depth correctionwith a linear function
Cut-based Qsum analysis
83MeV
55MeV# of events
# of events
In
55 MeV peak
no cut 260k 15k
55 MeV selection with
the other gamma
55k 8129
position selection
15026 1750
depth selection 3018 1362
78 %
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Energy Resolution
= 1.23 ±0.09 %FWHM=4.8 %
55 MeV
σ = 1.00±0.08 % FWHM=5.2%
83 MeV
Cut-based Qsum analysis
=1.53%
FWHM = 4.5 ± 0.3
=1.16 ± 0.06%
FWHM = 5.0 ± 0.6
CEX 2003 CEX 2004
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Linear Fit analysisLinear Fit analysis55 MeV event selection55 MeV event selection
Correlation with NaI/LysoCorrelation with NaI/Lyso
83 83 MeV in LXeMeV in LXe
55 55 MeV in LXeMeV in LXe
Y (cm)Y (cm)
X (cm)X (cm)
Small displacement (~ 0.5 cm)Small displacement (~ 0.5 cm)
Linear Fit analysis
In general it is possible to obtain higher In general it is possible to obtain higher efficiency with the linear fit analysisefficiency with the linear fit analysis
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Energy (Linear Fit) and Qsum reconstructionEnergy (Linear Fit) and Qsum reconstruction
Black: Linear FitBlack: Linear FitRed: QSUMRed: QSUMLinear Fit trained Linear Fit trained using MC including using MC including Fresnel reflection; Fresnel reflection; used Q.E. determined used Q.E. determined with six sources. No with six sources. No large differences large differences changing Q.E. set.changing Q.E. set.
The Linear Fit The Linear Fit works better. works better.
No selection, No selection, 600k events600k events NaI cut, NaI cut, 144k events144k events
NaI+sat cut, NaI+sat cut, 83k events83k eventsNaI+sat+coll cut, NaI+sat+coll cut, 54k events54k events
NaI cutNaI cut: : 70 MeV70 MeVQNAIQNAI100 MeV100 MeVColl. cut: Coll. cut: (X(X22 + Y + Y22))1/21/2 4.75 cm 4.75 cm
Linear Fit analysis
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Energy vs. DepthEnergy vs. DepthCorrection along X & YCorrection along X & Y
E (MeV)E (MeV)
Z (cm)Z (cm)
Red: all eventsRed: all events; ; Green: no saturatedGreen: no saturated
Remove ADC saturated events Remove ADC saturated events is equivalent to a depth cut.is equivalent to a depth cut.
Linear Fit analysis
We observed a We observed a slight position slight position dependencedependence of the of the reconstructed reconstructed Energy. Energy.
It can be corrected by using a It can be corrected by using a parabolic interpolationparabolic interpolation..
E (MeV)E (MeV)
E (MeV)E (MeV)
No NeedAnymore
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Saturation &Saturation &NaI cut + R<1.5 NaI cut + R<1.5 cmcm
FWHM = 4.8 %FWHM = 4.8 %
Reconstructed Energy (updated)
Correction (X&Y) effect Correction (X&Y) effect 0.3 % 0.3 %
Linear Fit analysis
83MeV
Saturation &Saturation &NaI cutNaI cut
FWHM = 5.6 %FWHM = 5.6 %
55MeV
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Position dependence of energy resolution
4.5 0.5 5.1 0.5 6.2 0.8
5.6 0.5 4.9 0.5 4.9 1.1
5.3 0.7 4.9 0.5 5.2 2.0
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Timing Analysis
Intrinsic, L-R analysis
Absolute, Xe-LYSO
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T = TDC - Tref TDC correction for time-walk and position
And correction for position TL, TR by weighted average of Ti
<T> = (TLTR)/2
The algorithm
PMT
i
iii Ni
Q
ctT ,1 ,
/1
/
,
,
1
2,
1
2,,
,
RL
RL
N
iRiL
N
iRiLRiL
RL
TT
i=r.m.s. of Ti
cut on Qi> 50 pe Left
Right
LPNaI S1
LYSO tLP - tLYSO
-
TL
TR
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Intrinsic resolution, L-R analysis
•Position and Tref
corrections applied
•Applied cuts:
• |x|< 5cm, |y|<5cm
• ELYSO+ENaI >20 MeV
• RF bunch and TDC sat.
•Study of vs Npe
• = 65 ps @ 35000 pe
• = 39 ps @100000 pe
•QE still to be applied
Old data
New data
L-R analysis
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Absolute resolution, Time reference (LYSO)
• LYSO PMT1 & 2
• Coorected for x-coord. (not for y)
• Corrections applied for time walk (negligible at high energy deposit)
PMT1 PMT2
Xe- LYSO analysis
LYSO
gamma
slitslit
(TLYSO(R) -TLYSO(L))/2
with 1cm slit
=64 psec
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Absolute timing, Xe-LYSO analysis55 M
eV
high gainnormal gain
110 psec 103 psec
Xe- LYSO analysis
LYSO Beam L-R depth reso.
110 64 61 = 65 = 56 33 psec
103 64 61 = 53 = 43 31 psec
No
rma
l g
ain
Hig
h
ga
in
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1st look on the waveform data
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DRS Setup
Two DRS chips were available.
10ch/chip (8 for data and 2 for calibration) in total 16 for data
2.5GHz sampling (400ps/sample)
1024 sampling cells Readout 40MHz 12bit Free running domino
wave stopped by trigger from LP
LP Front FaceDRS0 DRS1
Xe()
•DRS inputs•LP: central 12 PMTs•LYSO: 2 anode signals for each DRS chip as time reference
•DRS chip calibration
•Spike structure left even after calibration, which will be fixed by re-programming FPGA on the board.
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Simple Waveform Fitting
Simple function with exponential rise and decay can be nicely fitted to the xenon waveform. (and also LYSO waveform)
Other Fitting functions Gaussian tail
V(t)=A(exp(-((t-t0)/τrise)2)-exp(-((t-t0)/τdecay)2))
CR-RCn shaping V(t)=A((t-t0)/τdecay)n
exp(-(t-t0)/τdecay) Averaged waveform
template
Xenonτrise=7.0nsecτdecay=35nsec
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separation & LYSO timing
Alpha events are clearly discriminated from gamma events. This does not highly depend on the fitting procedure.
LYSO time resolution is similar to that obtained with TDC.
α
γ
Pulse height [mV]
Tim
e co
nst
ant
Pulse shape discriminationLYSO time resolution
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Averaged Waveform An averaged waveform can be used
for fitting as a template for simulating pileup for testing analysis algorithm etc.
The measured waveforms are averaged after synchronizing them with T0
Use the “template” for fitting! Pulse shape seems to be fairly constant for the
gamma event.
Average
-40mV -160mV -1200mV
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Simulation of Pileup Events
Overlapping pulses are simulated using averaged waveform to test rejection algorithm.
Real baseline data obtained by the DRSs is used.
Npe1=2000phe Npe2=1000phe (3000phe is typical for 50MeV gamma)
ΔT=-30nsec
ΔT=+30nsec ΔT=+60nsec
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Trial of Pileup Rejection
It seems easy to break up overlapping pulses >10ns apart from each other.
Rejection power is being investigated for different sets of (Npe1, Npe2) and ΔT.
Npe1=2000phe Npe2=1000phe
ΔT=-15nsec
ΔT=-10nsec
ΔT=-5nsec
ΔT=+15nsec
Ori
gin
al
Diff
ere
nti
al
easy Difficult but not impossible
?easy
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Cryogenic Equipment Preparation Status
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PC150W performance
Condition: 6.7kW(60Hz) 4Hz Twater=20 C (Iwatani 2003.12) 6.0kW(50Hz) 4Hz Twater>30 C (PSI 2004.7)
New PT(190W) andKEK original (65W)
Cool i ng power (PC150)
0
50
100
150
200
50 100 150 200
Col d end temperature(K)
Cooling power (W)
Qi wa(W)Qpsi (W)
at PSI
at Iwatani
Calorimeter operation without LN2 at PSI(Sep.to Oct.2004)42-day operation without degradation in cooling performance
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Current status/schedule of liquid-phase purification test
xenon
Liquidpump
Purifiercartridge
LP top flange
17/Jan wire installation & closing the cryostat
24/Jan setup in PiE5 -13/Feb evacuation 7-20/Feb liq. N2 piping 14/Feb-13/Mar
liquefaction and test 14/Mar recovery
•New calibration wires with higher intensity•9MeV gamma from Nickel
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End of Slide
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The algorithm TDC correction for time-walk and position (point-like approx)
vertex reco. by weighted average of PMTs (new QE set, see Fabrizio Cei’s talk) TL, TR by weighted average of Ti
<T> = (TLTR)/2
/1
/
,
,
1
2,
1
2,,
,
RL
RL
N
iRiL
N
iRiLRiL
RL
TT
i=r.m.s. of Ti
cut on Qi> 50 pe
PMTref
i
iii NiT
c
ind
c
z
Q
wTDCT ,1 ,
),(
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The algorithm
T9 F20
= (2905) ps = (345 5) ps
Side PMTs are less sensitive to z-fluctuations than Front PMTs
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TLXe - TLYSO
Global non-linear corrections for -vertex (50 ps)
mainly due to:
• scale compression (operated by PMT average)
• finite shower size
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Beam spot on target
Beam profile
• H = 13.2 mm
• V = 9.9 mm
(as measured by Peter)
62.3 ps