liquid xenon detector part i

Liquid Xenon Photon Detector Feb. 2004 MEG Review Meeting

Liquid Xenon DetectorPart I

• CEX beam test at piE1 Oct-Dec/03– Hardware operation status

– Analysis A. Baldini’s presentation

• Other related topics– Detector Calibration

– PMT R&D A. Baldini’s presentation

– Refrigerator

– Liquid phase purification

– Cryostat

Liquid Xenon Detector Group


Large PrototypeLarge Prototype• 70 liter active volume (120 liter LXe in us

e), 228 PMTs• Development of purification system for xe

non• 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 beam– 60MeV Electron beam– from 0 decay


CEX beam test at piE1


Elementary process

- (essentially) at rest captured on protons:

- p 0 n - p n

0

Photon spectrum

54.9 82.9 129MeV

M/2

M/2(1cos*)

M/2

*

E=55 MeV * =


Angular selection -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


Overview of the beam test

• 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 0 detected• 24/Oct empty target run• 1/Dec PMT amplifier study• 6/Dec Recovery• 7/Dec Cold xenon gas data for PMT

calibration

22/Sep

29/Sep

6/Oct

13/Oct

20/Oct

27/Oct

3/Nov

10/Nov

17/Nov

24/Nov

1/Dec

8/Dec

0 detected

Beam tuning

purification

pumping

Cooling/liquefaction

DAQ

~7weeks

Recovery Cold xenon gas data


• Beam line– Magic momentum (110MeV/c)– FSH52, 4mm carbon degrader (110

107MeV/c) in ASY51– 26mm carbon degrader in front of t

he target– S1 counter (40x40x5mm3) to defin

e the beam

• Area layout– The Electronics barrack placed in th

e area with concrete shielding around it.

– All controls and monitors done in the barrack.

– Liquid nitrogen supplied from a dewar located in the area.

E1 beam line

Proton beamTarget

ASY51


Setup

Carbon degrader

Lead Collimator at the beam line exit


Hydrogen Target

• 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– entrance

– exit

cell


NaI detector

• For tagging 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

A

B

C

D

E

F

G

H

8 7 6 5 4 3 2 1

For trigger

For trigger

Base Line

Stabilizer

Attenuator

x10

x10

ADC

Trigger

Box

TDC

Crystal Array

HV

Trigger module

Differential input stage

Differentiator, Attenuator and base line stabilizer

Output stage


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


NaIEnergy Estimation

Search for the NaI crystal with maximum charge

Charge sum in the surrounding NaI’s.

The Calibration parameter is determined by using 129MeV data. ( 37MeV/cosmic peak )

Raw Sum　　　

NaI with MaxQ

Reconstructed Energy

55MeV

83MeV

threshold

129MeV

• - p 0 n

0

(E = 55, 83MeV)

• - p n

(E = 129MeV)


NaIEnergy Resolution

• 55 MeV 7.0+/-0.13 %

• 83 MeV 6.5+/-0.14%

• 129 MeV 6.1+/-0.04%


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.

NaI with MaxQ

x 2.7cmy 1.6cm


- stopping distribution in the target must be considered in subtraction

Timing Counter• 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

5cm x 5cm x 1cm t

BC404

R5505

Viewed from the target

100mm

Lead collimator

TC

LPNaI S1

TCtLP - tTC

Pb

!


Timing Counterefficiency and resolution

• ~40% efficiency for 83MeV (> 1MeV deposit in the scinti.)

• 60 psec time resolution in sigma

55MeV

83MeV

129MeV

GEANT simulation

Ratio of events with > 1MeV deposit in the scintillator

(TC1-TC2)/2


Xenon Large Prototypeoperating condition

• Gain/QE calibration– LED and as usual

• PMT gain 106, 5x106

• Absorption length after 2 weeks purification abs > 140cm (90% C.L.)

(central value ~2.7m)

• 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


QE Calibration

The peak position is well reproduced by this MC code.

• 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 QE’s using the event.


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 (MSCB+LabView)

• Refrigerator control, Temp., Pressure Monitor

• Data set– Collimators in front of LP and NaI

( back to back)– Timing Counter (Pb+Scintillator) i

n front of NaI

Preamplifier Module

Av = 1

-In

+In

300

15050

CLC449

Av = +1

300

300

CLC44950

50

Av = -10

Discrete transistors

50

Av = +1

AD8001

32 Channels

8 units

Full-bandwidth Outs

Full-bandwidth Outs

Low range (x8 amplification)

Middle range

High range (20dB attenuation)


Trigger

• back-to-back 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

• data with opening angle < 180o

– NaI : QUAD module

• Very low threshold trigger for LP– One or two hit(s) in any one of 8 clusters

• , LED, cosmic-ray, pedestal triggers for calibration

123

4

5

6


Beam Condition• p(-)=107MeV/c

– Almost maximum separation (8nsec) of arrival time to the target between and , and between and e.

• Beam intensity– Up to 2.6 MHz @ 1800A

• Electron contamination in the beam– Negligible in triggered events

targetx=12mm

y=12mm

e/

~8nsec

TOF separation


0 signal example

LP ADC

NaI

AD

C

LP 83 MeV

NaI 55 MeV

LP 55 MeV

NaI 83 MeV


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 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.

events/ beam off

events/ beam on

Thermal neutron in Xe

•Absorption length ~ 3 cm• Capture close to calorimeter walls• Multi γ, ΣE(γ) = 9.3 MeV

PMTs used in LP do not have Al strip


Pulse Tube Refrigerator

1. Heat load and PT cryocooler 2. Further test and schedule


- Heat Load -

Heat LoadW@165K

Phase LXe(L)

PMT

Static PMT Cable

Total(W)

L.Proto 120 250 24 16 10 50Final 800 1000 20 65 45 130

-Based on the KEK-original PT cryocooler, Cryocooler with higher cooling power has been developed for the final calorimeter


Technology transfered to

Iwatani Co., Ltd

Designed:

150 W @165K

Large Power Pulse Tube Cryocooler



One for Columbia University

For Dark Matter SearchDesigned:

90 W@165K

3kWcompressor



Technology transfered to

Iwatani Co., Ltd.

Two for MEG

Designed:

150 W @165K

using 6.7kW compressor


Large Power PT Cryocooler-Cooling power at 6.7kW compressor-

PT150 Cooling Power

0

50

100

150

200

250

60 80 100 120 140 160 180 200

Temperature (K)

Cool

ing

Pow

er (

W)

Q150 (W)

Qkek(W)

KEK originalfor Large Proto

For final calorimeter6.7kW, 4Hz


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


Liquid Phase Purification


Liquid phase purification test

• Pump and purifier in the Large Prototype chamber– Very simple

– No worry about heat load


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


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


Purification systemin the final detector

LXe CalorimeterLiquid circulating purifier

Liquid pump (100L/h)

Purifier1000L storage dewar

Cryocooler (100W)

LN2

LN2

Getter+Oxysorb

GXe pump (10-50L/min)

GXe storage tank

Cryocooler (150W)

Heat exchanger

Gas phase purification

Liquid Phase purification


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.

motor

Outside of the cryostat

(room temp.)

Inside of the cryostat

(low temp.)

Impeller

Pump isolator


Cryostat Construction


Design goals:

-Design goals:-Independent test of the inner vessel and outer vessel during construction.-Implementation 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.


-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.

Windows material


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).

Walls/Cover Material DimensionPressureDirection

Design PressureMPa

Design Tempdegree C

ThicknessCalculation (mm)

Thickness Actual(mm)

Inner Vessel Inner Wall SUS316L R623 x L1086 Outer 0.3 -108~40 5.4 7.0Inner Vessel Outer Wall SUS316L R1116 x L1086 Inner 0.3 -108~40 3.0 7.0

Inner Vessel Front Wall SUS316L min504 x max1086 Inner 0.3 -108~40 23.0 24.0Inner Vessel Cover SUS316L R1148 x R588 Inner 0.3 -108~40 22.7 24.0

Outer Vessel Inner Wall SUS316L R550 x L1260 Inner 0.1 40.0 0.5 0.5Outer Vessel Outer Wall SUS316L R1200 x L1270 Outer 0.1 40.0 7.5 8.0Outer Vessel Front Wall SUS316L min650 x max1270 Outer 0.1 40.0 16.7 20.0Outer Vessel Cover SUS316L R1200 x R540 Outer 0.1 40.0 15.4 20.0


Heat Load Calculation

• See also T. Haruyama’s 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

Heat load calcluation for the xenon photon detector vessel

UnitRadiation Outer Vessel -> Inner Vessel (30 Mylar layers) 3.1 WConduction Nozzle (N1-N3) via xenon gas 0.2 WConduction Nozzle (N1-N3) via belows 4.6 WConduction Support (brace and supporting pipe) 6.3 WHeat generation PMT (65mW/PMT) 52 WConduction PMT HV and Signal Cables 50 Wtotal 116.2 W


Several modifications from the previous design


Photon Detector

2002 2003 2004 2005

Test MilestoneAssemblyDesign Manufactoring

Large Prototype Beam Test Beam Test

Vessel Design Assembly & Test

PMT Delivery + Testing

Refrigerator Manufactoring Assembly

Liq. Purification

Assembly Test

Manufactoring

Engineering runs


Summary

• CEX beam test was carried out at E1 area.– Analysis Results A. Baldini’s 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 E5 to see background condition and COBRA magnetic field effect.

liquid xenon detector part i

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