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LXe Beam Test Result

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LXe Beam Test Result

CEX beam test 2004

Cryogenic Equipment Preparation Status

Liquid Xenon Photon Detector Group

- 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

- 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

- 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

Eg

170o

q

Eg

Eg

p0

175o

q

54.9MeV

82.9MeV

1.3MeV for q>170o

0.3MeV for q>175o

Eg

- p-pp0n
- p0(28MeV/c) g g
- 54.9 MeV < E(g) < 82.9 MeV

- Requiring q>170o
- FWHM = 1.3 MeV

- Requiring q > 175o
- FWHM = 0.3 MeV

H2 target+degrader

LYSO

Eff ~14%

NaI

LP

S1

Eff(S1xLP)~88%

beam

- 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 x108п-/sec
- Slits 100: 3.95 x108 п - /sec

Optimization of degrader thickness

20mm + 3.3mm x n

Profile at S1, 2mm/bin

- Thanks to a new refrigeratorwe 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

- September

- And Waveform data…

Analysis Result

Calibration

Energy

Timing

1st look on waveform Data

Wire (50 μm ϕ)

Alpha

40 μm

- 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-life=138 days

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

LXe

GXe

Nphe[0]

Nphe[0] for top-left alpha

with alpha emission angle selection

Center of the PMT-0

4 front sources

Applying the QEs determined in GXe (-75˚C)

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

Energy Reconstruction

Cut-based Qsum Analysis

Linear Fit Analysis

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

Cut-based Qsum analysis

83 MeV to Xe

55 MeV to Xe

Exenon[nph]

MC

Cut-based Qsum analysis

83MeV

55MeV

Before depth correction

78 %

After depth correction

with a linear function

Cut-based Qsum analysis

CEX 2004

CEX 2003

55 MeV

s=1.53%

FWHM = 4.5 ± 0.3

- = 1.23 ±0.09 %
FWHM=4.8 %

83 MeV

s=1.16 ± 0.06%

FWHM = 5.0 ± 0.6

σ= 1.00±0.08 %

FWHM=5.2%

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

Linear Fit analysis

Y (cm)

Correlation with NaI/Lyso

83 MeV in LXe

55 MeV in LXe

X (cm)

Small displacement (~ 0.5 cm)

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.

NaI+sat cut, 83k events

NaI+sat+coll cut, 54k events

NaI cut: 70 MeV<QNAI<100 MeV

Coll. cut: (X2 + Y2)1/2< 4.75 cm

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.

Linear Fit analysis

83MeV

55MeV

Saturation &

NaI cut

FWHM = 5.6 %

Saturation &

NaI cut + R<1.5 cm

FWHM = 4.8 %

Correction (X&Y) effect 0.3 %

Timing Analysis

Intrinsic, L-R analysis

Absolute, Xe-LYSO

NaI

g

S1

g

LP

LYSO

tLP - tLYSO

p-

- T = TDC - Tref
- TDC correction for time-walk and position
- And correction for position
- TL, TR by weighted average of Ti
- <T> = (TLTR)/2

TL

i=r.m.s. of Ti

cut on Qi> 50 pe

Left

Right

g

TR

L-R analysis

- Position and Tref corrections applied
- Applied cuts:
- |x|< 5cm,|y|<5cm
- ELYSO+ENaI >20 MeV
- RF bunch and TDC sat.

- Study ofsvs Npe
- s= 65 ps @ 35000 pe
- s= 39 ps @100000 pe

- QE still to be applied

Old data

New data

LYSO PMT1 & 2

Coorected for x-coord. (not for y)

Corrections applied fortime walk (negligible at high energy deposit)

LYSO

slit

slit

gamma

Xe- LYSO analysis

(TLYSO(R) -TLYSO(L))/2

s=64 psec

PMT1

PMT2

with 1cm slit

Xe- LYSO analysis

high gain

normal gain

103 psec

110 psec

55 MeV

Normal gain

High gain

1st look on the waveform data

LP Front Face

DRS0

DRS1

- 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)

- 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

- Gaussian tail

τrise=7.0nsec

τdecay=35nsec

Xenon

Time constant

γ

α

Pulse height [mV]

- 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

- 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

- 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=+60nsec

ΔT=-30nsec

- 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

Original

ΔT=-10nsec

ΔT=-5nsec

ΔT=-15nsec

ΔT=+15nsec

Differential

?

easy

easy

Difficult but not impossible

Cryogenic Equipment Preparation Status

at Iwatani

- Condition:
- 6.7kW(60Hz) 4Hz Twater=20 C (Iwatani 2003.12)
- 6.0kW(50Hz) 4Hz Twater>30 C (PSI 2004.7)

at PSI

New PT(190W) and

KEK original (65W)

Calorimeter operation without LN2 at PSI(Sep.to Oct.2004)

42-day operation without degradation in cooling performance

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

End of Slide

- TDC correctionfor time-walk
and position (point-like approx)

vertex reco. by weighted average of PMTs

(new QE set, see Fabrizio Cei’s talk)

- TL, TRby weighted average of Ti
- <T> = (TLTR)/2

i=r.m.s. of Ti

cut on Qi> 50 pe

T9

F20

s = (2905) ps

s = (345 5) ps

Side PMTs are less sensitive to z-fluctuations than Front PMTs

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

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