Liquid Xenon Detector Part I

1
Liquid Xenon DetectorPart I

• CEX beam test at piE1 Oct-Dec/03
• Hardware operation status
• Analysis ? A. Baldinis presentation
• Other related topics
• Detector Calibration
• PMT RD ? A. Baldinis presentation
• Refrigerator
• Liquid phase purification
• Cryostat
• Liquid Xenon Detector Group

2
Large Prototype

• 70 liter active volume (120 liter LXe in use),
  228 PMTs
• Development of purification system for xenon
• Total system check in a realistic operating
  condition
• Monitoring/controlling systems
• Sensors, liquid N2 flow control, refrigerator
  operation, etc.
• Components such as
• Feedthrough,support structure for the PMTs,
  HV/signal connectors etc.
• PMT long term operation at low temperature
• Performance test using
• 10, 20, 40MeV Compton g beam
• 60MeV Electron beam
• g from p0 decay

3
CEX beam test at piE1
4
Elementary process
M?/2
? - (essentially) at rest captured on protons ?
- p ? ?0 n ? - p ? n ? ?0 ? ? ?
Eg55 MeV ? ? ?
5
Angular selection
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

6
Overview of the beam test
22/Sep
29/Sep
6/Oct
13/Oct
20/Oct
27/Oct
3/Nov
10/Nov
17/Nov
24/Nov
1/Dec
8/Dec
pumping

• 25/Sep Detector was moved to the area. evacuation
• 27/Sep- Beam tuning
• 29/Sep pre-cooling
• 2/Oct-5/Oct Liquefaction
• 5/Oct-29/Oct Purification(gas phase)
• 5/Oct- Electronics setup
• 15/Oct p0 detected
• 24/Oct empty target run
• 1/Dec PMT amplifier study
• 6/Dec Recovery
• 7/Dec Cold xenon gas data for PMT calibration

Cooling/liquefaction
Beam tuning
p0 detected
purification
DAQ 7weeks
Recovery
Cold xenon gas data
7
pE1 beam line

• Beam line
• Magic momentum (110MeV/c)
• FSH52, 4mm carbon degrader (110?107MeV/c) in
  ASY51
• 26mm carbon degrader in front of the target
• S1 counter (40x40x5mm3) to define the beam
• Area layout
• The Electronics barrack placed in the area with
  concrete shielding around it.
• All controls and monitors done in the barrack.
• Liquid nitrogen supplied from a dewar located in
  the area.

ASY51
Proton beam
Target
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Setup
Lead Collimator at the beam line exit
Carbon degrader
9
Hydrogen Target
g

• Thanks to Dr. J. Zmeskal.
• Liquid H2 cooled with a GM-refrigerator
• Temperature control
• Target cell
• 0.5mm t Al
• 40mm d x 100 L
• 125cc liquid hydrogen
• Kapton foil
• p entrance
• g exit

p
g
cell
p
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NaI detector
Crystal Array

• For tagging g at the opposite side of LP 8x8 NaI
  crystals
• 40.6x6.3x6.3cm3
• Located 110cm from the target
• Signal processor and Trigger Box (QUAD module) to
  provide trigger signal

Trigger module
HV
Differentiator, Attenuator and base line
stabilizer
Output stage
Differential input stage
ADC
Attenuator
Trigger Box
x10
x10
Base Line Stabilizer
TDC
11
NaICalibration

• High voltage value for each PMT is adjusted by
  using cosmic ray events.
• Pedestal subtraction Gain correction are done
  in the offline analysis.
• Energy and Vertex reconstruction are performed by
  using corrected charge information ? next slides.

Cosmic ray events
HV adjust Gain Correction
12
NaIEnergy Estimation

• Search for the NaI crystal with maximum charge
• Charge sum in the surrounding NaIs.
• The Calibration parameter is determined by using
  129MeV g data. (? 37MeV/cosmic peak )

Reconstructed Energy

• ? - p ? ?0 n
• ?0 ? ? ?
• (Eg 55, 83MeV)
• p- p ? n ?
• (Eg 129MeV)

55MeV
83MeV
Raw Sum
129MeV
NaI with MaxQ
threshold
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NaIEnergy Resolution

• 55 MeV 7.0/-0.13
• 83 MeV 6.5/-0.14
• 129 MeV 6.1/-0.04

14
NaIVertex Reconstruction

• Search for the NaI with maximum charge
• Fit the charge distribution of the raw or column
  (8 NaIs in each) that include NaI with maximum
  charge using a gaussian function.

4cm diam. collimator.
sx 2.7cm sy 1.6cm
NaI with MaxQ
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Timing Counter
5cm x 5cm x 1cm t BC404
R5505

• 2 layers of
• 5cm x 5cm x 1cm BC404
• Hamamatsu R5505 at both ends
• 3mm t Pb plate
• Time resolution can be estimated internally by
  TC1-TC2

g
S1
NaI
g
LP
Pb
g
TC
100mm f Lead collimator
tLP - tTC
p- stopping distribution in the target must be
considered in subtraction
!
TC
Viewed from the target
16
Timing Counterefficiency and resolution

• 40 efficiency for 83MeV g (gt 1MeV deposit in
  the scinti.)
• 60 psec time resolution in sigma

(TC1-TC2)/2
GEANT simulation Ratio of events with gt 1MeV
deposit in the scintillator
129MeV
83MeV
55MeV
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Xenon Large Prototypeoperating condition

• Xenon extracted from the chamber is purified by
  passing through the getter.
• Purified xenon is returned to the chamber and
  liquefied again.
• Circulation speed 5-6cc/minute

• Gain/QE calibration
• LED and a as usual
• PMT gain 106, 5x106
• Absorption length after 2 weeks purification
• labs gt 140cm (90 C.L.)
• (central value 2.7m)

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QE Calibration

• Gas xenon data had been used for calibration
  because the absorption can be ignored in gas.
• W-values are equivalent in gas and liquid?
• Established purification scheme provided very
  pure xenon.
• Possible to evaluate PMT QEs using the a event.

The peak position is well reproduced by this MC
code.
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Data Acquisition

• Hardware setup
• ADC 3 ranges for front-face PMTs
• 2 ranges for the others
• TDC for all PMTs
• PMT amplifier (x10)
• BINP
• Lecce
• Software
• Online MIDAS
• Slow control (MSCBLabView)
• Refrigerator control, Temp., Pressure Monitor
• Data set
• Collimators in front of LP and NaI (gg back to
  back)
• Timing Counter (PbScintillator) in front of NaI

Middle range
Low range (x8 amplification)
High range (20dB attenuation)
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Trigger

• back-to-back gg data
• NaI sum signal of the central 4 crystals
• LP sum signal of
• 8 PMTs on the front face 4 PMTs on the back
  face
• gg data with opening angle lt 180o
• NaI QUAD module
• Very low threshold trigger for LP
• One or two hit(s) in any one of 8 clusters
• a, LED, cosmic-ray, pedestal triggers for
  calibration

5
1
6
3
2
4
g
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Beam Condition

• p(p-)107MeV/c
• Almost maximum separation (8nsec) of arrival time
  to the target between p and m, and between p and
  e.
• Beam intensity
• Up to 2.6 MHz _at_ 1800mA
• Electron contamination in the beam
• Negligible in triggered events

target
sx12mm
TOF separation
sy12mm
8nsec
p
e/m
22
p0 signal example
LP 55 MeV g NaI 83 MeV g
NaI ADC
LP 83 MeV g NaI 55 MeV g
LP ADC
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Background Condition

• Background events
• most probably caused by beam-related neutrons,
• Energy deposit up to 9-10MeV,
• Corresponding to 1.5x106 p.e./sec
• Beam on/off
• PMT output for a events changes, reduced to 70
  of normal values at full intensity beam rate
  (less reduction at lower intensity)
• Not due to bleeder current shortage but due to
  photocathode saturation because we observed the
  same effect even with lower PMT gain.

a events/ beam off
PMTs used in LP do not have Al strip
a events/ beam on

• Thermal neutron in Xe
• Absorption length 3 cm
• Capture close to calorimeter walls
• Multi ?, SE(?) 9.3 MeV

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Pulse Tube Refrigerator

• Heat load and PT cryocooler
• Further test and schedule

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- Heat Load -
-Based on the KEK-original PT cryocooler,
Cryocooler with higher cooling power has been
developed for the final calorimeter
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Large Power Pulse Tube Cryocooler
Technology transfered to Iwatani Co.,
Ltd Designed 150 W _at_165K
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Large Power Pulse Tube CryocoolerOne for
Columbia University
For Dark Matter Search Designed 90 W_at_165K
3kWcompressor
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Large Power Pulse Tube Cryocooler
Technology transfered to Iwatani Co., Ltd. Two
for MEG Designed 150 W _at_165K using 6.7kW
compressor
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Large Power PT Cryocooler-Cooling power at 6.7kW
compressor-
For final calorimeter 6.7kW, 4Hz
KEK original for Large Proto
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Results and Further Tests
-Achieved cooling power of 190W at 165K (6.7kW
compressor) -Orientation dependence test...
Horizontal layout for the case of two cold
head -Another phase shift configuration (Double
Inlet) test... To increase cooling power
Schedule
-January 2004 Final parameter fixed -February
2004 Fabrication will start -March 2004 Will
be delivered (two sets) -Can be installed for the
LXe liquid purification test
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Liquid Phase Purification
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Liquid phase purification test

• Pump and purifier in the Large Prototype chamber
• Very simple
• No worry about heat load

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Implementation in the final detector

• Xenon from the bottom bypass the wall to the
  pump/purifier
• Easy maintenance
• Possible heat load to the bottom
• ? Next slide

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Realization of the system

• Verification of liquid phase purification
• Large Prototype is the best to show the
  purification performance
• Long term operation in the final detector
• Heat load to the bottom must be minimized

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Purification systemin the final detector
Gas phase purification
Liquid Phase purification
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Status

• Fluid pump was delivered to a Japanese
  manufacturer.
• Assembling the pump and purifier cartridge for
  verification.
• The system will be tested using the LP.

Impeller
motor
Pump isolator
Outside of the cryostat (room temp.)
Inside of the cryostat (low temp.)
37
Cryostat Construction
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Design goals
-Design goals -Independent test of the inner
vessel and outer vessel during construction. -Impl
ementation of a draining system. -A
simplification of the supporting system (three
legs.) and a limiting displacement system -Adding
a pre-cooling system on the inner vessel
covers. -Adding a safety valve on the outer
vessel for positive pressure. -Adding a rohacell
sheet between the outer thin window and the
magnet structure for positive pressure.
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Windows material
-Problem with high strength austenitic stainless
steel. -To obtain high yield we need a stress
hardening process that causes a slight
ferromagnetic characteristic that can be removed
by a special heat treatment. -Size of the sheet
can be another problem. -The austenitic ss with
the nitrogen should have a better strength and a
better magnetic characteristic.
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Thickness of the Walls/Covers

• Suppose the pressure tolerance of 0.3MPa for the
  inner vessel and 0.1MPa for the outer vessel
  (vacuum insulation layer).

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Heat Load Calculation

• See also T. Haruyamas talk on Jul 2002 review
  meeting.
• Main contribution is from PMT and cables.
• One pulse tube refrigerator can compensate the
  load.
• Possibility of mounting two refrigerator is now
  investigated

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Several modifications from the previous design
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Photon Detector
2002
2003
2004
2005
Large Prototype
Beam Test
Beam Test
Engineering runs
Vessel Design
Assembly Test
Manufactoring
PMT Delivery Testing
Assembly
Test
Refrigerator
Manufactoring
Assembly
Liq. Purification
Test
Milestone
Assembly
Design
Manufactoring
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Summary

• CEX beam test was carried out at pE1 area.
• Analysis Results ? A. Baldinis presentation
• Liquid Phase Purification test will be done in
  2004.
• Refrigerator will be assembled and delivered
  soon.
• Cryostat design renewal.
• Plan in 2004
• LP operation in pE5 to see background condition
  and COBRA magnetic field effect.