Development of a Cherenkov timing detector for measuring high-intensity secondary...
Transcript of Development of a Cherenkov timing detector for measuring high-intensity secondary...
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Development of a Cherenkov timing detector for measuring high-intensity secondary beams
K. Shirotori and T. Akaishi
for the E50 collaboration
Research Center for Nuclear Physics (RCNP)
Osaka University
3rd Symposium on Clustering as a window on the hierarchical structure of quantum systems
18th May 2020
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Contents
• Introduction• Effective degree of freedom of hadrons: X* & W* spectroscopy
• High-momentum K- beam @ J-PARC High-p beam line
• High-rate Cherenkov timing detector: R&D status• High-intensity beam measurement by fine-segmented detector
• Time resolution evaluation of proto-type detectors
• To do
• Summary
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Introduction
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Investigation of effective degree of freedoms
• To understand role of effective degree of freedoms for hadrons• Diquark correlation, molecule states
• Systematic studies: Charmed baryon (q-q + Q) ⇔ X* (q + QQ) and W* (QQQ) systems• Heavy (heavier) quarks are key.
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3q baryonMeson baryon
(Molecule)
Pentaquark
(Multi quark)
Q
q-q
q
Q Q
Q
X*
W*
Yc*
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Experimental situations of X* and W* baryons
• Poor experimental data of X* and W*
• Systematics studies are essential.
• Narrow decay width expected
⇒ Chance to find and separate states• G ~ a few 10 MeV of X* < a few 100 MeV of L*/S*
• W* expects to have also narrow width.
⇒ Systematics measurements• Production and decay
*K- beam is effective tool to produce multi-strangeness baryons.• High-momentum beam: 5-10 GeV/c
• Large yield: s = ~1 mb order and high-rate beam
⇒ Systematic studies by E50 spectrometer• Beam measurement is essential for missing mass and decay measurement
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E50 spectrometer
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1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
0 2 4 6 8 10 12 14 16 18 20
[GeV/c]
Design Intensity [Hz] in spill (2.0 sec)
High-momentum beam line for 2ndary beam
• High-intensity beam: > 1.0×107 Hz p (< 20 GeV/c)• Unseparated beam: p/K/pbar : MHz K beam ⇔ 100 MHz p beam
• Beam timing measurement: Start timing
⇒ “Bottleneck” to increase beam intensity
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@ 15 kW loss
0.E+00
5.E-03
1.E-02
2.E-02
2.E-02
0 2 4 6 8 10 12 14 16 18 20
[GeV/c]
K/p & pbar/p ratio
K-/p-
pbar/p-
2%p-
pbar
K-
MHz K beam
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High-momentum beam line for 2ndary beam
• High-intensity beam: > 1.0×107 Hz p (< 20 GeV/c)• Unseparated beam: p/K/pbar : MHz K beam ⇔ 100 MHz p beam
• Beam timing measurement: Start timing
⇒ “Bottleneck” to increase beam intensity
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1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
0 2 4 6 8 10 12 14 16 18 20
[GeV/c]
Design Intensity [Hz] in spill (2.0 sec)
p-
pbar
@ 15 kW loss
MHz K beam
K-
• High-rate capability
• Good time resolution
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High-rate Cherenkov timing detector: R&D status
Fine segment test
Signal processing method test
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T0 detector
• Segment by Acrylic (PMMA)
⇒ Cross shape: X-type• Cherenkov angle direction
• Suppress time spread
• Both edge readout• ×2 light yield
• 3-mm width segment + MPPC• MPPC amplifier: ~10 ns width
⇒ Time resolution: DT ~ 50 ps(rms)• 3 MHz/segment ⇒Achieved• No position dependence*Akaishi master thesis
*Limit: ~3 MHz/3-mm segment
⇒ < 1-mm width fine segment• Handle 100 MHz beam
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Front view
Beam
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T0 detector
• Segment by Acrylic (PMMA)
⇒ Cross shape: X-type• Cherenkov angle direction
• Suppress time spread
• Both edge readout• ×2 light yield
• 3-mm width segment + MPPC• MPPC amplifier: ~10 ns width
⇒ Time resolution: DT ~ 50 ps(rms)• 3 MHz/segment ⇒Achieved• No position dependence*Akaishi master thesis
*Limit: ~3 MHz/3-mm segment
⇒ < 1-mm width fine segment• Handle 100 MHz beam
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3 mm < 1 mm
Front view
30 MHz by 3-mm segment 100 MHz by 1-mm segment
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Simulation: Radiator width dependence• Fine segment simulation
• Geant4: Optical photon• Realistic parameters: PMMA, MPPC and so on
• Normalization of # of p.e.• 3-mm radiator light yield data⇒ Reflection probability of PMMA: 99.5%
• Light yield is decreased by fine segments.• ~16 p.e. @ 0.5 mm
• Smaller loss of fast components• Small number of reflections
• Resolution is expected to be kept.
*Production by company • Cut from one PMMA board
⇒Actual fine segment test
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× < 50 ps
× < 100 ps
× < 150 ps
× < 200 ps
All P.E.
Single edge P.E.
Simulation image
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Fine segments of Cherenkov radiator
• Radiators can be fixed by Silicone sheet with glue and some wires.
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3.0 mm 1.0 mm 0.5 mm
Cross section
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Test experiment @ LEPS
• Purposes
• Fine segment test
• 1.0 mm and 0.5 mm segments
• New amplifier test
• Signal processing test
• Schottky Barrier Diode filter circuit
• Integration circuit for TOT
• Time resolution evaluation by MIP• e± from g-ray conversion
• RF timing reference: DT ~14 ps
• Time walk correction by pulse height• Data taking: DRS4 and HUL HR-TDC
• MPPC (s13360-3050PE) conditions: Vov = +7V
• One p.e. pulse height: ~70 mV (amp gain: ×18.8)
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Beam
Reference counters
New amplifier
(Test type)
T0 radiator
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Number of photoelectrons
• Average: ~20 p.e.
• Light yield tendency of both edge is consistent.
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Xup Xdown
Xup Xdown
Xup Xdown
3.0 mm
1.0 mm
0.5 mm
T. Akaishi, Master thesis
Beam
Number of photoelectrons (measured)
Xup
Xdown
20 mm high from center
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Number of photoelectrons
• Average: ~20 p.e.
• Light yield tendency of both edge is consistent.
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Xup Xdown
Xup Xdown
Xup Xdown
3.0 mm
1.0 mm
0.5 mm
T. Akaishi, Master thesis
Beam
Number of photoelectrons (measured)
Xup
Xdown
*Handwriting curbs
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Number of p.e.: @ +20 mm
• Sum of both edge and its distribution are same.
⇒ Collection of Cherenkov lights w/o surface loss
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Xup Xdown
Xup Xdown
Xup Xdown
3.0 mm
1.0 mm
0.5 mm
38.7± 0.4 p.e.
(s = 7.8 p.e.)
Sum of both Edge
40.4± 0.5 p.e.
(s = 7.8 p.e.)
38.6± 0.7 p.e.
(s = 8.0 p.e.)
+
+
+
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Time resolution: @ Vth = 3.5 p.e.
• All data: Similar time resolution of ~45 ps(rms).• Time resolution is kept. = Same light yield
*3.0 mm ⇒ 0.5 mm: ×6 higher counting rate• 3 MHz/3 mm @ 30 MHz ⇒ 3 MHz/0.5 mm @ 180 MHz
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3.0 mm 1.0 mm 0.5 mm
*RF DT ~14 ps(rms) subtracted
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38.7± 0.4 p.e.
Sum of both Edge
40.4± 0.5 p.e.
38.6± 0.7 p.e.
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R&D issues of T0 detector
1. Ringing suppression
• Effects to time resolution by pile-up signal
• Time resolution: 43 ps⇒ 54 ps @ High-rate condition
⇒ Schottky Barrier Diode (SBD)
was used as kind of filtering methods.
2. TOT measurement
• Time-walk correction
by Time-Over-Threshold (TOT) method
• Width = (Leading edge – Trailing edge)
• Only TDC measurement without ADC
• Dead-time less digitalization for streaming DAQ
18Pileup event
Ringing
Trigger timing
Time-Over-Threshold (TOT) method
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Schottky barrier diode: SBD• Kind of rectifier diode
• Quick responses• Smaller forward voltage: 100-200 mV level
*Revered pulses and smaller pulses are suppressed.
⇒ Ringing suppression
• BAT63: Series connection to amplifier• Signals width: Same• Vout = 0.62×(Vin) – 70.0 (Minimum input: ~120 mV)
19I-V characteristic
MPPC amp
SBD circuit
Series connection
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Time resolution: W/o and W/ SBD
• Similar time resolution of ~45 ps(rms).• W/ SBD data showed little worse resolution.• Smaller pulse height affected by noise
• SBD can be used as filter circuit. ⇒ High-rate test
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*RF DT ~14 ps(rms) subtracted
W/o SBD W/ SBD
*Horizontal axis: ±0.3 ns
Ringing
Trigger timing
・ W/o SBD
×W/ SBD
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Time-Over-Threshold method
• Straight forward method cannot correct time-walk of leading edge.
• Differential circuit for narrow signal width
⇒Width is saturated in the higher pulse height region.
*Extract pulse height information from width
⇒ Integration by slow shaping
• SBD + slow shaping is essential.
• RC integration circuit
• t = 2.4 ns
• R = 51 W, C = 47 pF
• Signal width: ~15 ns
• Original: ~10 ns
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VINVOUT
GND GND
R
C
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Time resolution: TOT method
• Width analysis showed similar resolution. @ Vth = 4.5 p.e.• Response is not completely understood by using amplifier w/ SBD and RC circuit.
⇒ Investigation of optimum time constant
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・ Pulse height
×Width
*Vth = 3.5 p.e. data
⇒ Correlation is almost same as of
Vth = 4.5 p.e. data.
⇒ It is necessary to investigate.
By width
*Tail component
*RF DT ~14 ps(rms) subtracted
By PH
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To do*To finalize R&D and production of Cherenkov beam timing detector
• Tests in early 2020 are affected by COVID-19.• Segmented detector test by EMPHATIC @ Fermilab (Postponed by November)
⇒ Test at other facilities (LEPS, ELPH ?)
• High-rate test @ ELPH ⇒ It will be performed in July(?) or October (?).
+ Test by mixed signal: Emulate pile-up events
• Investigate and optimization of filtering circuit• SBD and RC circuit
• Design of actual detector• Segment width size adjustment for beam profile
• Simulation study for fixing radiators with good filling rate
• MPPC array (TSV type) for assembling fine segments
• Publication plan• X-shape Cherenkov detector: 1st draft is under preparation.
• High-rate measurement: Signal processing, TOT and so on
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8 ch MPPC board
TSV MPPC array (1 mm)
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Summary
• Investigation of effective degree of freedom for hadrons• Systematic study: Charmed baryon ⇔ X and W
• K- beam @ J-PARC High-p beam line• High-intensity K- beam ⇒ Dominant p in unseparated beam
• High-rate capability of beam timing detector: Fine segment beam detector
• R&D of Cherenkov timing detector• X-shape Acrylic radiator with thin width: 0.5 mm, 1.0 mm, 3.0 mm
• Test experiment @ LEPS
⇒ Time resolutions of ~45 ps(rms) were kept by using fine segment radiators.
• Availability of much higher counting rate beam: ×6 higher rate
• 3 MHz/3 mm @ 30 MHz ⇒ 3 MHz/0.5 mm @ 180 MHz
• Filtering method test for suppressing ringing effects by SBD
• High-rate test is necessary for finalizing R&D.
• TOT method test: SBD + Integration circuit
• It was found that measurement without ADC can be performed.
*To finalize R&D and production of Cherenkov beam timing detector• K- beam intensity is as high intensity as possible at J-PARC high-momentum beam line.
⇒ To drive investigation of multi-strangeness baryons
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