OBJECTIVES: Feasibility study of INO prototype detector ( RPC ) of dimension 1m 3
Beam Test of Moller Main Detector Prototype
Transcript of Beam Test of Moller Main Detector Prototype
Beam Test of Moller Main Detector Prototype
Peiqing WangMichael Gericke
University of Manitoba
Moller Collaboration MeetingOct. 22, 2013
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Prototype Detector Geometry
Schematics (not in scale)
PMT
5 cm
4 cm
8.4
cm
30 cm 25, 35 or 60 cm
PMT/base Housing Light Guide
Quartz
4 cm
2.54
cm
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Quartz Radiators
Size: 8 cm x 6 cm x 2.5 cm
Identification:
Q1: with a single 45 deg cut
Q2: with two 45 deg cuts
Q3: no angle cut
2.5 cm6
cm
8 cmQ1 Q2 Q3
The cutted side is facing light guide Hand-polished (not in high quality)3 different shapes to test which one has the best light yield
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Light Guide & PMT Housing
8 light guides were built with different materials and lengthes
● UVS: 25 cm, 35 cm, 60 cm● Miro-2: 25 cm, 35 cm● Miro-Silver: 25 cm, 35 cm, 60 cm
A wider light guide opening (4 cm) allows to fit thicker quartz (2.54 cm) with different tilt angles
A larger PMT housing (30 cm x 9 cm x 9 cm) allows to hold 3” or 2” PMT and base
Considering the flexibility of changing configurations for prototype tests ...
60 cm 35 cm
25 cm
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Light Guide and Quartz Housing
Looking inside from the opening of PMT housing(the bright shining part is the light guide section)
Quartz housing:
● Small container to hold our short quartz piece
● Easier to change light guide with a spearated quartz housing
● Top trapezoid section allows quartz to tilt from 0 to 45 deg
● Bottom section fits the shape of light guide
“top endcap + black tape + bottom endcap” to make it light tight
Considering the flexibility of changing configurations for prototype tests ...
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Quartz and Detector Mounting
Quartz mounting:● Alllowing to mount quartz at different
orientation angles (0 – 45 deg)● Easily to exchange quartz
Detector mounting:● Allowing to mounting detector at different
orientation angles and positions(30, 45, 60, 90, 120, 135 and 150 deg)
● With ability to adjust height
Quartz mounting bracket
Detector mounting structure
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Photomultiplier Tube9305KFL (SN509) by ElectronTubes
3 inch (78 mm), active diameter 70 mm
Operating HV: 1700 V (maximum)
High QE at UV band
Quantum Efficiency of 9305KFL (SN509)
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Beam Test Setup at MAMI Facility
Side View Looking Downstream
● Detector tilted 45 deg from beam pipe● Beam going throung quartz
● Detector tilted 135 deg from beam pipe● Beam going throung light guide
● Mounted on a 2D motion table (range: horizontal 0 – 14 cm, vertical 0 – 10 cm)● Light guide tilt angle was defined as the angle between beam pipe and light guide
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Electronics/DAQ
Detector
Scintillator 1
Scintillator 2
Disc
Disc
Amplifier
And
Delay
Delay
QDC
gate
ch0
ch1
● Ch1 is an amplified copy of Ch0
● QDC: CAEN V965, ~900 pC full range
● Trigger rate: 3 – 5 kHz, typical run time: 300 s
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Tests and Studies Performed
● Calibrations (QDC sensitivity, amplifier gain and SPE)● Light yield with the most “realistic” configuration● Hit-position-dependent light yield● Detector excess noise● Effects of quartz polishing quality● Light guide length and material● Quartz & LG geometry● Quartz wrapping material● Lead pre-radiator, effects of shower in quartz and in LG● Background events in light guide● Blacked-out LG studies● PMT type selection
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Calibration: QDC Sensitivity, Amplifier Gain and SPE
QDC (CAEN V965) sensitivity: 0.2 pC/chcalibrated by using 120pC charge pulser
Amplifier Gain: 13.7determined by comparison of non-amplified signals in channel 0 and amplified signals in channel 1
SPE charge: 0.35 +/- 0.07 pC (at normal operating HV - 1250 V)
Method 1 (cross-calibration technique): 0.3 pC/PE Directly observed SPE (~2.7 pC/PE at 1.7 kV) by pushing PMT to its highest gain, then cross-calibrated it back to its normal operating HV (1250 V) via two fixed configuration runs at both high and low HVs. Uncertainty depends on fit quality.
Method 2 (LED calibration technique): 0.4 pC/PE, Uncertainty depends on fit quality.
Method 3 (statistical method): 0.42 pC/PE, This is the upper bound of SPE charge, calculated from measured detector resolution.
Taking average of 1 & 2, then imposing a systematic error bar on the average so that it can reach the upper bound, i.e. SPE = 0.35 +/- 0.07 pC
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The Most “Realistic” Configuration
Configuration:
PMT: SN509HV: 1250 VSPE: 0.35 pC/PE in ch0 at 1250 Vquartz: 1 cm thick, wrapped with white paper, single 45 deg cut at light guide sideLG: Miro Silver 25 cm, 45 deg tilt vs beamQDC: CAEN V965, sensitivity 0.2 pC/ch
PMT
beam
Test the Umass' 1 cm thick, well-polished quartz in Manitoba light guide
● This configuration was mostly close to the intended design of Moller ring detector
● Configuration differences between simulation and beam test:
Simulation Beam Test
Light guide UVS, 35 cm long Miro-Silver, 25 cm long
Quartz 1.5 cm thick 1 cm thick
PMT Low QE Higher QE in UV band
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Run#410
Ped: 61.9
Gaussian fit:Peak: 117.4Sigma: 11.2
● Simulation expectation: 37 PE ( for 1.5 cm thick quartz) 25 PE ( for 1.0 cm thick quartz)
(ref. p.21, Moller DocDB#76-v1)
● Data: (117 - 62) x 0.2 pC/ch / (0.35+/-0.07) pC/PE = 31 PE (or 26 - 39 PE)
● Good agreement. A little bit higher #PE yield in test data can be attributed to shorter light guide, better reflectivity, and higher PMT QE
Full spectrum with pedestal removed:Mean: 121.1RMS: 16.7
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Hit-Position-Dependent Light Yield – Horizontal Scan
● Beam position scan from left to right on quartz (beam's eye view)
● Yield increases a little when beam moving to the light guide side; this could attribute to the polishing quality of quartz.
● As expected, yield decreases at the slope on quartz, and is propotional to the the thickness of quartz
Light guide side
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Hit-Position-Dependent Light Yield – Vertical Scan
● Beam position scan from bottom to top on quartz (beam's eye view, here from left to right)
● #PE yield reaches maximum at quartz center
● The yield differences is ~7%; this could also attribute to the polishing quality of quartz.
beam
quartz
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Excess Noise
● Beam energy: 0.9 GeV
● Data point at 1 cm thickness of quartz was obtained from UMass' well-polished quartz
● Mean and RMS were obtained from pedestal-removed QDC spectrum
Simulation Expectation: ~5%
Beam Test Data: <6%
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Quartz Geometry
beam
beam
● Both configurations used a same Miro-Silver 25 cm long light guide
● Single-cut quartz (Q1) has better performance
● #PE Yield ratio: 81.7%
Q1
Q2
PM
T
PMT
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Quartz Wrapping Material
No wrapping
Mylar
Whitepaper
● #PE yield ratio: 1 : 1.9 : 3.2 (No wrapping : Mylar : White paper)
● Large effect on #PE yield (due to quartz polishing quality?)
PMT
beam
Quartz: Manitoba Q1 (2.5 cm)LG: Miro-Silver 25 cmPMT: 3” (ET #509)
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Quartz Polishing Quality
PMT
beam1 cm thick quartzwell polished
2.5 cm thick quartzhand-polished
● #PE Yield ratio (2.54 cm quartz: 1 cm quartz):
2.17 : 1
● Loss due to polishing quality:
(2.54 - 2.17)/2.54 = ~15%
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Lead Pre-radiator
PMT
beam
● Lead pre-radiator (1.5 cm thick) increases the #PE yield by a factor of 5.6
● Excess noise:~5% (no lead)~10% (with lead)
1.5 cm thick lead
no lead
with lead
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Light Guide Length
60 cm long Miro-Silver(run#109)
25 cm long Miro-Silver(run#58)
Compare the yields of 60 cm and 25 cm light guides:
#PE Yield Ratio: 68%
PMT
beam
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Light Guide Material
25 cm long UVS(run#184)
25 cm long Miro-Silver(run#182)
Compare the yields of UVS and Miro-Silver 25 cm light guides:
#PE Yield Ratio: 92.6%
beam
Miro-Silver is 7% better than UVS
PM
T
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Light Guide Events
● Red: "1 cm quartz + 1.5 cm lead" in front of light guide. Because this "shower-booster" was 45 deg tilted w.r.t. beam, it is equivlent to:
1.4 x (1 cm quartz + 1.5 cm lead)
● Green: 1.0 cm thick quartz in front of light guide, ~1.4 cm equivlent thickness due to 45 deg tilting angle
● Blue: no pre-rad material in front of light guide.
● bkg events can be clearly seen,
● the upstream shower from quartz and lead increased these bkg events dramatically (quantitative studies needed).
full range is about 200 PEs
PMT
beam
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Blacked-out Light Guide
beam
PM
T
25 cm long light guide lining with black Kapton
Using “black” light guide to test: contributions from the “line-of-sight” photons
#PE yield ratio:
~9% (kapton : Miro-Silver)
black Kapton light guide
Miro-Silver light guide
More than 90% detected photons propogate via the reflection of light guide
(note: black kapton is not an ideal material for blacked-out)
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Blacked-out Light Guide
Red: Miro-Silver 45 deg
Green: Kapton, 45 deg
Blue: beam-off pedestal
Comparison of light guide events in Miro-Silver light guide and blacked-out light guide
beam
PM
T
25 cm long light guide lining with black Kapton
● Tails above pedestal can be seen
● Black Kapton light guide has a smaller tail
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Blacked-out Light Guide
beam
PM
T
Light guide Lining: black Kapton
Cyan: 90 deg
Red: 45 deg
Blue: 90 deg with 1 cm thick quartz in front
Green: 135 deg
PMT
PMT
45 deg 90 deg 135 deg
Comparison of blacked-out light guide events at different light guide orientation angles
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PMT Type
Blue (3” PMT):
● ET 9305KFL● Active diameter: 70 mm● High QE (~30%) at UV● Shorter light guide: 25 cm
Red (2” PMT)
● Photonis XP2268● Active diameter: 44 mm● Lower QE at UV● Longer light guide: 35 cm
2” PMT
3” PMT
For comparison:
● Normalized● Converted to #PE
#PE yield:
● 2” - 17.3 PE● 3” - 65 PE (or >55 PE)
#PE yield ratio 3.75 : 1
(PMT acceptance: 2.53 : 1 )
From simulation, an effective way to increase the #PE yield is to increase PMT acceptance
Test configuration: Q1 quartz (1inch), Miro-Silver light guide with 45 deg orientation angle
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Conclusion
● A fruitful test beam experiment - many studies were performed
● Not all tests are covered here; data for a few more configurations are available for analysis
● Preliminary analysis showed a general agreement between beam test data and detector simulation expectations
● For a configuration with 1 cm thick, well-polished quartz, we obtained
#PE > 25, excess noise ~4%
● Light guide events were confirmed; further quantitative studies are needed
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Calibration of QDC Sensitivity and Amplifier Gain
QDC: CAEN V965, 900 pC full range
Charge of pulse: 120 pC
Pedestal is in channel 136.1
Peak of charge pulses is in channel 737.9
QDC sensitivity: 120 pC/(737.9 - 136.1) = 0.2 pC/ch
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no amplifier
with amplifier
Determination of Amplifier Gain
● Ch0: no amplifier
Ch1: amplified copy of ch0
● Fit pedestal and peak
Ch1 mean – ped.● Gain = ------------------------- = 13.7 Ch0 mean – ped.
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Configuration:
PMT: SN509HV: 1250 VSPE: 0.35 pC/PE in ch0 at 1250 VQuartz: 2.5 cm thick, wrapped with white paper, single 45 deg cut at light guide sideLG: Miro Silver 25 cm, 45 deg tilt vs beamQDC: CAEN V965, sensitivity 0.2 pC/ch
PMT
beam
Using the 1 inch thick quartz
#PE Yield of the “Best” Configuration
#PE Yield: 65 PE
(or 55 – 82 PE if taking into account the uncertainty of SPE calibration)