Transcript PID upgrade of BESIII

Upgrade of PID for BESIII
June 13, 2006
Institute of High Energy Physics, Beijing, China
Yuekun Heng ([email protected])
BESIII
Outline
 Present TOF design
 Physics requirements for PID
 Upgrade to MRPC??
 Upgrade to Internally reflecting
Cherenkov detector:
CCT, TOP, Focusing DIRC
 Summary and discussion
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1. Present TOF Design
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Present barrel TOF
The option of barrel TOF is determined after many
discussions in June, 2005. Two layers of scintillator will
be used for barrel.
CsI
Calorimeter
Barrel
TOF
Drift
Chamber
Endcap
TOF
Barrel TOF alignment
Fig. BTOF side view. To save
space, the base of PMT
housing is 6-sides-shaped and
the inner and outer layer is
across. It has four screws to
connect the scin.
Fig. Assembly of barrel TOF.
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Endcap TOF structure
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Analysis of Time reso.
Non TOF ~
ps
60
Item
Barrel time
reso.
Endcap time
reso.
Intrinsic time reso. of one TOF layer
for 1 GeV muon
80~90 ps
80 ps
Uncertainty from electronics
25 ps
25 ps
Uncertainty from bunch length
15 mm，35
ps
15 mm，35
ps
Uncertainty from bunch time
~20 ps
~20 ps
Uncertainty from Z position
5 mm,25 ps
10 mm,50 ps
Resolution of expected time of flight
30 ps
30 ps
Total time reso, one layer of TOF for
1 GeV muon
100~110 ps
110~120 ps
Total time reso, double layer of TOF
for 1 GeV muon
90 ps
Why two layers?
 Time reso. For Kaon and
pion is worse 20% than
muon in experiences.
 Time reso. Of two layers
totally is from 100ps to
110ps for kaon and pion.
 That time reso. Can
separate kaon/pion of
0.9GeV in the middle of
barrel.
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Time reso.
For
Kaon/pion
Contriburion
Time reso.
For 1GeV
Muon
Non TOF
60ps
One layer of
scin. Intrinsic
80-90ps
One layer of
Scin. Totally
100-110ps
110ps-130ps
Two layers,
Totally
80-90ps
100ps-110ps
Capability of separation
of Kaon and Pion
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2. Physics targets for PID
and our space limits
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K/πmomentum on BESIII
 BEPCII: 2.0~4.2GeV
 BESIII:


Charm physics:J/Psi,
Psi’, Psi’’
Tau Physics
 K/π momentum:
almost all<1.5GeV
 K/π seperation:
1.2GeV is enough
 Present TOF:
0.9GeV(2sigma,95%)
Next target
Momentum distribution for
hadrons at J/psi
Experimental Searching for
D0D0 Mixing (From He Kanglin )
 Big challenge to PID (Kπchannel)

Main backgrounds come from the double
miss-PID
 Searching in semi-leptonic decay modes
are experimental difficulty with 2
missing neutrino (hard to reduce
background contribution to 10-4)
 Monte Carlo study with different PID
(TOF resolution)
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Detection efficiency vs
TOF resolution
Efficiency vs time resolution
efficiency(%)
40
38
36
34
32
30
60 65 70 75 80 85 90 95 100 105 110 120 130
Time resolution(ps)
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Background rates vs
TOF resolution
Background(10-4)
Background vs time resolution
5
4
3
2
1
0
60 65 70 75 80 85 90 95 100 105 110 120 130
Time resolution(ps)
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PID space limits
 Banded to MDC
outer barrel of
Carbon-fiber
 R-direction space:
81cm-92.5cm
 Scintillator Length:
2320mm
 Coverage:~82%
PID
space
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3. Upgrade to MRPC??
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Target analysis for MRPC
 To get 1.2GeV separation of K/pi, totally time reso.
<80ps
 Non-TOF is 60ps, TOF <60ps,
Plastic scin. Can’t give so good time.
MRPC may be OK.
 To cover dead area of MRPC, overlap of two layers of
MRPC is needed.
 To reduced electronics, MRPC should be long strip and
readout by two ends.
 Long-strip MRPC needs much more studies.
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MRPC results
试验
尺寸cm
时间分辨
VEPPW
e+e-
小尺寸
0.1mm缝隙
75ps（流光模式）
NA49
4X30
0.1mm缝隙）
50ps（流光模式）
HARP
200X15X1
140-180ps
9.1X180
(long strip)
70-80ps（束流试验
）
STAR
24X22X9
60ps（束流试验）
ALICE
120X13X2.5
FOPI
Upgrade
Timing
RPC R&D
160X10X20
(long strip)
38ps
50-75ps
束流试验
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III.
4 gaps, 0.3mm/gap
HV:10kV/mm
Preamp: not say
GAS: 85% C2H2F4
5% iso- C4H10
10%SF6，
达到的时间分辨为75ps
MRPC option
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bakelite as the resis. plate
Structure:
•Resi. Plate: bakelite
•gaps: 6;
•Chamber: 8cm(W)X190cm(L)
•gas：90%Freon, 5%iso-butane,
5%SF6
•Preamp：Star
Signal pulse
•HV: 16kV/1.2mm)
•Readoud pad:3X6cm
•Rise time:~2ns
•Time Reso.:70～110ps
The results for a MRPC sample where the
fish-line is rolled in longitude direction
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Our tests
钓鱼线竖绕板室
钓鱼线竖绕板室的初步实验结果（吴金杰）
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Structure:
•Resi. Plate: bakelite
•gaps: 6;
•Chamber: 8cm(W)X190cm(L)
•gas：90%Freon, 5%iso-butane,
5%SF6
•Preamp：Star
Signal pulse
•HV: 16kV/1.2mm)
•Readoud pad:3X6cm
•Rise time:~2ns
•Time Reso.:~110ps
Reasons: gap not well
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钓鱼线横绕的MRPC实验结果（安正华）
两边气槽和边框共占去3cm，有
效面积约65％。
MRPC signal
T-Q correction
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14.5kV MRPC: Time reso.
上图是MRPC幅度谱在100－400的时间分辨
由此可计算出MRPC的本征时间分辨
sqrt(3.907*3.907-2.837*2.837)*25ps=67.16ps
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14.5kV MRPC 实验总结 时间分辨
上图是MRPC幅度谱在401－2047的时间分辨
由此可计算出MRPC的本征时间分辨
sqrt(6.709*6.709-2.926*2.926)*25ps=150.93ps
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4. Internally reflecting
Cherenkov detector:
CCT, TOP, Focusing DIRC
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Cherenkov detectors
Name
Principle
Range of
PID
readout
美国 SLAC
Babar－DIRC
[2]
Quartz + long bar +
Water tank + PMT
～4GeV
11000 PMT，
日本 KEK
BELLE －ACC
[3]
ACC, Threshold type
～3.5GeV
2000 Fine-Mesh
PMT
美国
CLEO-III
RICH[4]
LiF as the radiator,TEA gas
to convert photon-electron,
MWPC to detect the ring of
cherenkov
～2.8GeV
230,000 channels
electronics
CERN
LHC-b RICH
[5]
Two RICHs. RICH1: 5cm thick
ACC and 95cm thick C4F10 as
radiator;RICH2: 180cm thick
CF4 as radiator
～150GeV
Hybrid
PhotoDiode, Much
space
CERN LEP
DELPHI RICH
[6]
Gas of C5F12 and liguit of
C6F14,as radiator,
~25GeV
gas photodetector
+ MWPC to readout
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Internally reflecting cherenkov detector
 Using internally
reflecting cherenkov
light
 Parameters to know:



track direction
Cherenkov light(x,y), or
(theta, phi)
Transmitting time:
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3 options (refers to Honscheid ,Ohshima,Vavra,)
CCT(Cherenkov Correlated Timing )
• 1D Timing only
a) Time is related to
cherenkov angle
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CCT
 Its principle is to measure the time
of the cerenkov light to separate
particles.
 We did simulations. There are
about 10 PEs for 2inches PMT with
QE of 20%. reso.
 Transit time spread of PMT:



Line-focus type PMT, 250ps (xp2020)
Fine-mesh type PMT, 180ps (R5924)
Micro-Channel-Plate type PMT, 50ps
(R2809U)
Potential of CCT:
MCP-PMT to give good time reso.
Refer to:Jochen Schwiening, SLAC
T. Ohshima, Nagoya Univ.
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Comparison of K/ sep.
 TOF+TOF
Fig. K / separation for Double TOF
 TOF+CCT
Fig. K / separation for TOF+CCT
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TOP: Time of Propagation
 Principle: only Φcandθc can determine
cherenkov angle. TOP and Φ can deduce
them.
Quartz
bar’s sides are vertical and
conserve the Φc. Quartz lightguide is
needed to ensure the light direction out of
quartz bar
Fucussing
Mirror: fucussing the parrel
light because of the thickness of quartz
bar.
Photon
detector is placed opposite of
mirror.
To
deduce dead area, the detection end
will be placed in opposite ends for
adjacent counters
Uncertainties
of TOP
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 Chromatic error. 5‰。
 Uncertainty of Φc. Mirror’s





resolution and PMT position
resolution, can be 9mrad.
Time spread of PMT
Start time resolution
Thickness of quartz bar. High
speed particle transmit quartz bar
(20mm) needs about 66ps. But
when particle inclined transmits,
the uncertainty will be reduced
because particle transit time and
light transit time lessen it.
Position of injected particle.
~2mm，~10ps
Photon electron number
2GeVπ ， position:0.02m 和 1m 处 . TOP
resolution VS Φ.By Ohshima.
Cherenkov ring by Y.Enari Using TOP.
Particle 4GeVπ，position:1m.
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TOP: Candidate of Super Belle
Refer to Peter Krizan, Super B
factory workshop, Frascati, 2006
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TOP:
Refer to Noriaki Sato, 2005, hawaii
For BESIII, 1.2 GeV is enough, 1.5
GeV is very good.
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Focusing DIRC




Measure the time and
2dimension position
It uses APD or MCP
PMT to measure the
time and position of
Cerenkov light from
Quartz.
No big imaging
circles and so no
much space is needed.
The money is saved
because of smaller
quantity of PMT.
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Candidate of Babar’s next plan
From Vavra,
Hawaii workshop
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5. Summary
 1.2GeV K/Pi separation is needed for BESIII




physics. Now it is only 0.9GeV. Upgrade is
nessesary.
<60ps of Long-strip MRPC is OK to give
1.2GeV separation. Experiments is under way.
60ps is not easy.
CCT has good potential for the upgrade. It is
simple with MCP-PMT of good time reso.
TOP can give over 1.5GeV separation of K/pi.
Focusing DIRC needs more space, impossible
for BESIII
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The End
Thanks a lot!
BESIII
K/Pi difference of cherekov light