Transcript Document 7561633

LXe Beam Test Result
CEX beam test 2004
Cryogenic Equipment Preparation Status
Liquid Xenon Photon Detector Group
1/41
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
2
PMT Development Summary
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
3
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
4
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
5
CEX Elementary process
p-pp0n
p0(28MeV/c)  g g
54.9 MeV < E(g) < 82.9 MeV
•
FWHM = 1.3 MeV
q
Eg
Eg
p0
Eg
•
Requiring q > 175o
FWHM = 0.3 MeV
54.9MeV
170o
Requiring q>170o
82.9MeV
1.3MeV for
q>170o
0.3MeV for
q>175o
175o
q
Eg
6
Beam Test Setup
H2 target+degrader
LYSO
Eff ~14%
NaI
LP
S1
Eff(S1xLP)~88%
beam
7
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:
 Slits 100:
2.07 x108 п -/sec
3.95 x108 п - /sec
Optimization of degrader thickness
20mm + 3.3mm x n
8
Profile at S1, 2mm/bin
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 precooling 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
9
Data set
Gain
ADC gate
Beam intensity
event# *
Low
-
middle
32 + 29** k
high
-
low
-
middle
48 k
high
-
low
55 k
middle
110 + 44** k
high
-
low
77 k
middle
85 k
high
47 k
400 nsec
High
600 nsec
400 nsec
Normal
600 nsec
And Waveform data…
10
Analysis Result
Calibration
Energy
Timing
1st look on waveform Data
11/41
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
12
Source Position Reconstruction
The two wires on the front face are a little displaced
LXe
GXe
13
Alpha data analysis
Nphe[0]
Nphe[0] for top-left alpha
with alpha emission
angle selection
Center of the PMT-0
14
LXe/MC, absorption length evaluation
4 front
sources
Applying the QEs determined in GXe (-75˚C)
15
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
16
Energy Reconstruction
Cut-based Qsum Analysis
Linear Fit Analysis
17/41
Cut-based Qsum analysis
Cut-based Qsum analysis
Event Selection
 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
Exenon[nph]
83 MeV to Xe
55 MeV to Xe
18
Cut-based Qsum analysis
Correction and selection efficiency
83MeV
55MeV
Before depth correction
55k
8129
15026
1750
3018
1362
# of events
no cut
55 MeV
selection with
the other
gamma
position
selection
depth selection
After depth correction
with a linear function
260k
# of events
In
55 MeV
peak
15k
78 %
19
Cut-based Qsum analysis
Energy Resolution
CEX 2003
=1.53%
55 MeV
CEX 2004
FWHM = 4.5 ± 0.3
= 1.23 ±0.09 %
FWHM=4.8 %
=1.16 ± 0.06%
83 MeV
FWHM = 5.0 ± 0.6
σ = 1.00±0.08 %
FWHM=5.2%
20
Linear Fit analysis
Linear Fit analysis
55 MeV event selection
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)
21
Linear Fit analysis
Energy (Linear Fit) and Qsum reconstruction
No selection, 600k events
NaI+sat cut, 83k events
NaI cut, 144k events
Black: Linear Fit
Red: QSUM
NaI+sat+coll cut, 54k events
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 cut: 70 MeV<QNAI<100 MeV
Coll. cut: (X2 + Y2)1/2 < 4.75 cm
22
Linear Fit analysis
Energy vs. Depth
Correction along X & Y
E (MeV)
E (MeV)
E (MeV)
Red: all events; Green: no saturated
No Need
Anymore
We observed a slight position
dependence of the reconstructed
Energy.
Z (cm)
Remove ADC saturated events
is equivalent to a depth cut.
It can be corrected by using a
parabolic interpolation.
23
Linear Fit analysis
Reconstructed Energy (updated)
55MeV
83MeV
Saturation &
NaI cut
Saturation &
NaI cut + R<1.5 cm
FWHM = 5.6 %
FWHM = 4.8 %
Correction (X&Y) effect  0.3 %
24
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
25
Timing Analysis
Intrinsic, L-R analysis
Absolute, Xe-LYSO
26/41
The algorithm
p-
 T = TDC - Tref
 TDC correction for time-walk and position
ci
Ti  ti 
,
Qi
i  1, N PMT
 And correction for position
 TL, TR by weighted average of Ti
g S1
NaI
g
LP
LYSO tLP - tLYSO
N L ,R
TL , R 
2
T
/

 iL,R iL,R
i 1
N L ,R
2
1
/

 iL,R
i=r.m.s. of Ti
cut on Qi> 50 pe
TL
Left
i 1
 <T> = (TLTR)/2
Right
g
TR27
L-R analysis
Intrinsic resolution, L-R analysis
•Position and Tref
corrections applied
•Applied cuts:
Old
data
New
data
• |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
28
Xe- LYSO analysis
Absolute resolution, Time reference (LYSO)
(TLYSO(R) -TLYSO(L))/2
PMT1
PMT2
•
•
•
=64 psec
LYSO PMT1 & 2
Coorected for x-coord.
(not for y)
LYSO
Corrections applied for
time walk (negligible at
high energy deposit)
slit
slit
gamma
29
with 1cm slit
Xe- LYSO analysis
Absolute timing, Xe-LYSO analysis
high gain
normal gain
55 MeV
Normal
gain

High
gain
103 psec
110 psec
110
103
LYSO Beam
64
64
61 = 65
61 = 53
L-R
= 56
= 43
depth reso.
33 psec
31 psec
30
1st look on the waveform data
31/41
DRS Setup
LP Front Face
DRS0 DRS1
 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 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 reprogramming FPGA on the board.
Xe(g)
32
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
(t-t0)/τdecay)
 Averaged waveform
 template
exp(-
Xenon
τrise=7.0nsec
τdecay=35nsec
33
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.
Time constant
Pulse shape discrimination
LYSO time resolution
γ
α
34
Pulse height [mV]
Averaged Waveform
 An averaged waveform can be used
 for fitting as a template
 for simulating pileup
 for testing analysis algorithm etc.
Average
 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.
-40mV
-160mV
-1200mV
35
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
36
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.
Original
Npe1=2000phe Npe2=1000phe
ΔT=-10nsec
Differential
ΔT=-15nsec
ΔT=-5nsec
ΔT=+15nsec
?
easy
Difficult but not impossible
easy
37
Cryogenic Equipment
Preparation Status
38/41
PC150W performance
Cooling power (W)
at Iwatani
200
150
Qiwa(W)
Qpsi(W)
100
50
0
New PT(190W) and
KEK original (65W)
50

Cooling power (PC150)
100
150
200
Cold end temperature
(K)
at PSI
Condition:


6.7kW(60Hz) 4Hz Twater=20 C (Iwatani 2003.12)
6.0kW(50Hz) 4Hz Twater>30 C (PSI 2004.7)
Calorimeter operation
without LN2 at PSI(Sep.to
Oct.2004)
42-day operation without degradation
in cooling performance
39
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
40
xenon
End of Slide
41/41
The algorithm
 TDC correction for time-walk
and position (point-like approx)
zg nd (g , i)
wi
Ti  TDCi 
Qi

c

c
 Tref ,
i  1, N PMT
vertex reco. by weighted average of PMTs
(new QE set, see Fabrizio Cei’s talk)
 TL, TR by weighted average of Ti
N L ,R
TL , R 
2
T
/

 iL,R iL,R
i 1
N L ,R
2
1
/

 iL,R
i=r.m.s. of Ti
cut on Qi> 50 pe
i 1
 <T> = (TLTR)/2
42
The algorithm
T9
 = (2905) ps
F20
 = (345 5) ps
 Side PMTs are less sensitive to z-fluctuations than Front PMTs
43
TLXe - TLYSO
Global non-linear corrections
for g-vertex (50 ps)
mainly due to:
• scale compression (operated
by PMT average)
• finite shower size
44
Beam spot on target
Beam profile
• H = 13.2 mm
• V = 9.9 mm
(as measured by Peter)
 p  62.3 ps
45