LXe Beam Test Result

1
LXe Beam Test Result

• CEX beam test 2004
• Cryogenic Equipment Preparation Status
• Liquid Xenon Photon Detector Group

2
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

3
PMT Development Summary
4
Alpha sources on wires

• 4 tungsten wires plated with Au (50 micron f)
• 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

wire
LED
gamma
5
New Refrigerator (PC150W)

• MEG 1st spin-off
• Technology transferred to a manufacturer, Iwatani
  Co. Ltd
• Performance obtained at Iwatani
• 189 W _at_165K
• 6.7 kW compressor
• 4 Hz operation

6
CEX Elementary process
p-p?p0n p0(28MeV/c) ? g g 54.9 MeV lt E(g) lt
82.9 MeV

• Requiring qgt170o
• FWHM 1.3 MeV
• Requiring q gt 175o
• FWHM 0.3 MeV

7
Beam Test Setup
H2 targetdegrader
LYSO Eff 14
NaI
LP
S1
Eff(S1xLP)88
beam
8
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 ? -/sec
• Slits 100    3.95 x108 ? - /sec

Optimization of degrader thickness 20mm 3.3mm x
n
Profile at S1, 2mm/bin
9
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
• 1821 Pre-cooling (72 hrs)
• 2124 Liquefaction (79 hrs)
• 24 Circulation start (30 cc/min)
• 24 Electronics setup
• October
• DAQ started
• 25 DRS boards installed
• 29 Recovery of xenon

10
Data set

• And Waveform data

11
Analysis Result

• Calibration
• Energy
• Timing
• 1st look on waveform Data

12
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

Po half-life138 days
13
Source Position Reconstruction

• The two wires on the front face are a little
  displaced

LXe
GXe
14
Alpha data analysis
Nphe0
Nphe0 for top-left alpha
with alpha emission angle selection
Center of the PMT-0
15
LXe/MC, absorption length evaluation
4 front sources
Applying the QEs determined in GXe (-75C)
16
Q.E. evaluation with alpha events in liquid

• Q.E. evaluation using alpha data in the liquid is
  also possible.
• Higher light yield ? Expected better evaluation
  if xenon is pure!

R9288
R6041
Data 8528 normal gain front 4
alphas MC reflection on quartz on no
absorption scattering length 45cm for 175 nm
17
Energy Reconstruction

• Cut-based Qsum Analysis
• Linear Fit Analysis

18
Cut-based Qsum analysisEvent Selection
Cut-based Qsum analysis

• Analyze only central events to compare with the
  previous result
• Xrec, Yreclt2cm
• 70 MeV lt ENaIELYSO lt 105MeV
• Sigma2 gt 40 (discard events if shallow)
• Sigma2 broadness of the event measured by using
  front face PMTs ? depth parameter

83 MeV to Xe
55 MeV to Xe
Exenonnph
MC
19
Correction and selection efficiency
Cut-based Qsum analysis
83MeV
55MeV
Before depth correction
78
After depth correction with a linear function
20
Energy Resolution
Cut-based Qsum analysis
CEX 2004
CEX 2003
55 MeV
s1.53 FWHM 4.5 0.3

• 1.23 0.09
• FWHM4.8

83 MeV
s1.16 0.06 FWHM 5.0 0.6
s 1.000.08 FWHM5.2
21
Linear Fit analysis55 MeV event selection
Linear Fit analysis

• In general it is possible to obtain higher
  efficiency with the linear fit analysis

Y (cm)
Correlation with NaI/Lyso
83 MeV in LXe
55 MeV in LXe
X (cm)
Small displacement ( 0.5 cm)
22
Energy (Linear Fit) and Qsum reconstruction
Linear Fit analysis
No selection, 600k events
NaI cut, 144k events
Black Linear Fit Red QSUM Linear Fit trained
using MC including Fresnel reflection used Q.E.
determined with six sources. No large differences
changing Q.E. set. The Linear Fit works better.
NaIsat cut, 83k events
NaIsatcoll cut, 54k events
NaI cut 70 MeVltQNAIlt100 MeV Coll. cut (X2
Y2)1/2 lt 4.75 cm
23
Energy vs. DepthCorrection along X Y
Linear Fit analysis
E (MeV)
E (MeV)
E (MeV)
No Need Anymore
Red all events Green no saturated
We observed a slight position dependence of the
reconstructed Energy. It can be corrected by
using a parabolic interpolation.
Z (cm)
Remove ADC saturated events is equivalent to a
depth cut.
24
Reconstructed Energy (updated)
Linear Fit analysis
83MeV
55MeV
Saturation NaI cut FWHM 5.6
Saturation NaI cut Rlt1.5 cm FWHM 4.8
Correction (XY) effect ? 0.3
25
Position dependence of energy resolution
26
Timing Analysis

• Intrinsic, L-R analysis
• Absolute, Xe-LYSO

27
The algorithm
p-

• T TDC - Tref
• TDC correction for time-walk and position
• And correction for position
• TL, TR by weighted average of Ti
• ltTgt (TL?TR)/2

TL
?ir.m.s. of Ti cut on Qigt 50 pe
Left
Right
g
TR
28
Intrinsic resolution, L-R analysis
L-R analysis

• Position and Tref corrections applied
• Applied cuts
• xlt 5cm, ylt5cm
• ELYSOENaI gt20 MeV
• RF bunch and TDC sat.
• Study of s vs Npe
• s 65 ps _at_ 35000 pe
• s 39 ps _at_100000 pe
• QE still to be applied

Old data
New data
29
Absolute resolution, Time reference (LYSO)
Xe- LYSO analysis
(TLYSO(R) -TLYSO(L))/2
s64 psec
PMT1
PMT2

• LYSO PMT1 2
• Coorected for x-coord. (not for y)
• Corrections applied for time walk (negligible at
  high energy deposit)

with 1cm slit
30
Absolute timing, Xe-LYSO analysis
Xe- LYSO analysis
high gain
normal gain
110 psec
103 psec
55 MeV
Normal gain
High gain
31
1st look on the waveform data
32
DRS Setup

• DRS inputs
• LP central 12 PMTs
• LYSO 2 anode signals for each DRS chip as time
  reference

• 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

• DRS chip calibration
• Spike structure left even after calibration,
  which will be fixed by re-programming FPGA on the
  board.

Xe(g)
33
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)/trise)2)-exp(-((t-t0)/tdecay)2
  ))
• CR-RCn shaping
• V(t)A((t-t0)/tdecay)n exp(-(t-t0)/tdecay)
• Averaged waveform
• template

trise7.0nsec
tdecay35nsec
Xenon
34
a/g 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.

Pulse shape discrimination
LYSO time resolution
35
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
-160mV
-1200mV
-40mV
36
Simulation of Pileup Events

• Overlapping pulses are simulated using averaged
  waveform to test rejection algorithm.
• Real baseline data obtained by the DRSs is used.

Npe12000phe Npe21000phe (3000phe is typical for
50MeV gamma)
?T30nsec
?T60nsec
?T-30nsec
37
Trial of Pileup Rejection

• It seems easy to break up overlapping pulses
  gt10ns apart from each other.
• Rejection power is being investigated for
  different sets of (Npe1, Npe2) and ?T.

Npe12000phe Npe21000phe
Original
?T-10nsec
?T-5nsec
?T-15nsec
?T15nsec
Differential
?
easy
easy
Difficult but not impossible
38
Cryogenic Equipment Preparation Status
39
PC150W performance
at Iwatani
at PSI
New PT(190W) and KEK original (65W)

• Condition
• 6.7kW(60Hz) 4Hz Twater20 C (Iwatani 2003.12)
• 6.0kW(50Hz) 4Hz Twatergt30 C (PSI 2004.7)

Calorimeter operation without LN2 at PSI(Sep.to
Oct.2004) 42-day operation without degradation in
cooling performance
40
Current status/schedule of liquid-phase
purification test

• 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

Purifier cartridge
Liquid pump

• New calibration wires with higher intensity
• 9MeV gamma from Nickel

LP top flange
xenon
41
End of Slide
42
The algorithm

• TDC correction for time-walk
• and position (point-like approx)
• vertex reco. by weighted average of PMTs
• (new QE set, see Fabrizio Ceis talk)
• TL, TR by weighted average of Ti
• ltTgt (TL?TR)/2

?ir.m.s. of Ti
cut on Qigt 50 pe
43
The algorithm
T9
F20
s (290?5) ps
s (345 ?5) ps
? Side PMTs are less sensitive to z-fluctuations
than Front PMTs
44
TLXe - TLYSO

• Global non-linear corrections for g-vertex (?50
  ps)
• mainly due to
• scale compression (operated by PMT average)
• finite shower size

45
Beam spot on target

• Beam profile
• sH 13.2 mm
• sV 9.9 mm
• (as measured by Peter)
• ?? sp 62.3 ps