Download C1 and C2 are threshold Cerenkov counters filled with CO 2 , for

PID, trigger and DAQ
for the GLAST beam test
(preliminary study)
Nicola Mazziotta
INFN Bari
[email protected]
Dec. 6, 2005
Scope
Particle identification and trigger layout
to be used in the PS and SPS beam test
Cerenkov
Nicola Mazziotta, Dec. 6, 2005
2
Requirement
• PS:
–
–
–
–
–
Photon beam via bremsstrahlung
Electron beam: energy
Hadron beam: energy
Muon beam: energy
PID rejection: TBD
• SPS:
–
–
–
–
–
4 angles (0, 20, 40 and 60 deg)
6 positions
6 energies (10, 20, 50, 100, 200 and 300 GeV)
Particle type: electrons, hadrons, muons
PID rejection: TBD
Nicola Mazziotta, Dec. 6, 2005
3
PS Particle type and intensity
Electrons, hadrons, muons
Momentum
(GeV/c)
Electrons
(%)
Hadrons
(%)
-1
60
40
-2
40
60
-3
30
70
-5
10
90
-5 ÷ -15
few
95
Muon fraction few %
Nicola Mazziotta, Dec. 6, 2005
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Threshold Cerenkov counters filled with CO2
• Electron selection in all range
• Muon selection from 2 GeV/c
• Pion selection from 3 GeV/c
• Kaon selection from 10 GeV/c
Nicola Mazziotta, Dec. 6, 2005
• Proton below the Cerenkov
threshold up to 16 GeV/c
5
Electron tagging with threshold Cerenkov counters
PS T9 Beam
C1 (CO2) 5 m long
C2 (CO2) 3 m long
C1 and C2 are threshold Cerenkov counters filled with CO2, for each
energy the CO2 pressure has been set to select the Electrons
Electrons = C1 * C2
Nicola Mazziotta, Dec. 6, 2005
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Electron tagging by threshold Cerenkovs
Beam
C1 (CO2) 5 m long
C2 (CO2) 3 m long
EM CAL
The hadron contamination in the electron sample is due to the interaction of particles with the
Cerenkov materials, that can produce delta rays with enough energy to generate Cerenkov photons.
Any background can also simulate fake electrons. An external system EM CAL (Pb Glass) is needed
to evaluate the hadron (pion) contamination in the electron sample
Electrons
Pions
Pion contamination in the electron sample is few %
Nicola Mazziotta, Dec. 6, 2005
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Hadron tagging with threshold Cerenkov counters
PS T9 Beam
C1 (CO2) 5 m long
C2 (CO2) 3 m long
C1 and C2 are threshold Cerenkov counters filled with CO2, for each
energy the CO2 pressure has been set to select the Electrons+Muons
(p > 2 GeV/c)
Hadrons = (C1 + C2),
Electron/Muon contamination in the
hadron sample = (1- 1) (1-2) fe/f
(< 10-3 from 3 to 6 GeV/c).
Nicola Mazziotta, Dec. 6, 2005
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Proton tagging with threshold Cerenkov counters
PS T9 Beam
C1 (CO2) 5 m long
C2 (CO2) 3 m long
C1 and C2 are threshold Cerenkov counters filled with CO2, for each
energy the CO2 pressure has been set to select the Kaons from 12 GeV/c
Protons = (C1 + C2)
Electron/Muon/Kaon/Pion
contamination in the proton sample
= (1- 1) (1-2) (f+fK+ fμ+fe)/fp (< 10-3
from 2 to 8 GeV/c).
Nicola Mazziotta, Dec. 6, 2005
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HARP Proton tagging by Cerenkov counters
PS T9 Beam
C1 (N2) 5 m long
Nicola Mazziotta, Dec. 6, 2005
C2 (N2) 3 m long
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Hadron tagging by TOF system
m1, m2, p
L
Proton/Kaon
Muon/Electron
Kaon/Pion
Pion/Electron
Pion/Muon
3 sigma resolution
1.00E+02
L = 10 m, sigma = 100 ps
1.00E+01
Delta TOF (ns)
1.00E+00
1.00E-01
1.00E-02
1.00E-03
1.00E-04
0
1
2
3
4
5
6
7
8
9
10
Beam momentum (GeV/c)
Nicola Mazziotta, Dec. 6, 2005
11
Observed particle fractions in the T9 beam by
HARP experiment (L=21.4 m)
proton contamination
in positron sample
Nicola Mazziotta, Dec. 6, 2005
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PS T9 beam area
In The T9 beam area maybe there is not enough space to install a
TOF, i.e. TOF could tag proton from kaon up to 2 GeV/c
Nicola Mazziotta, Dec. 6, 2005
13
Electron/Hadron idetification by TRD
Particle ID is based on the threshold properties of the TR
gsat
gth
Electron/pion identification: 1-100 GeV
Pion/proton identification: few 100 GeV - 1 TeV
Nicola Mazziotta, Dec. 6, 2005
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TRD performance vs length
The hadron contamination at 90% electron identification
efficiency can be reduced from about 0.1 to < 10-3 by
increasing the TRD length from 20 cm to 100 cm
Nicola Mazziotta, Dec. 6, 2005
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TRDs for particle identification
•
TRDs have been used to discriminate
electron/hadron or pion/proton in test beams or in
running experiments (accelerators or astrophysics):
rejecton factor ~ 10-3 (off-line)
•
Starting from the beginning of '90 years there have
been extensive research and developments to build
TRDs able to discriminate high rate beam particles
and work also as first level trigger devices
–
E769 at Fermilab (1991): the trigger time jitter was ~150 ns
and the /p rejection factor was ~ 3%, momenta (250- 500
GeV/c) and beam intensities of 30 kHz - 2 MHz
–
Fast TRD (1999): trigger device in a electron/hadron CERN
SPS beam (NA57)
Nicola Mazziotta, Dec. 6, 2005
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TRDs for high energy hadron beam
(as trigger or veto)
Fast-TRD for SPS-beam (1999):
1. pions/kaons/protons beam < 500 GeV/c (4 MHz rate),
2. 16 modules radiator (C-fibers)/double straw tubes layer (Xe-CO2)
3. time jitter of 40 ns
4. pion (proton) contamination about 1 % @ 90% electron (pion) efficiency
Nicola Mazziotta, Dec. 6, 2005
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Fast-TRD for SPS-beam: trigger layout
LeCroy 3412 16 Channel 200MHz Discriminator:
Current Sum Outputs: Rear-panel Lemo connector;
high impedance current source; generates a current
proportional to the input multiplicity at the rate of -1
mA+/-10% per hit (-50 mV per hit into a 50 ohm load);
The Mod. CAEN N408 is a NIM module which performs
the function of a logic adder on 24 independent input
NIM signals. Each true input signal gives a contribution
of 50 mV on an internal analog adding section
Nicola Mazziotta, Dec. 6, 2005
to TRIGGER
or
to VETO
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Fast-TRD: e/ beam
pions contamination about 1 % @ 90% electron efficiency
e vs  as trigger
e
 vs e as veto

e

e/ ~ GeV/c
/p ~ 100 GeV/c
For more details see NIM A 455 (2000) 305
Nicola Mazziotta, Dec. 6, 2005
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TRD system acquisition
LeCroy 3412 16 Channel 200MHz Discriminator:
Rear-panel Lemo connector; high impedance
current source; generates a current proportional
to the input multiplicity at the rate of -1 mA+/10% per hit (-50 mV per hit into a 50 ohm load);
16 Modules
VME ADC (CAEN V792 16/32 Channel Multievent
Charge ADC; 50 Ohm impedance, negative polarity, DC
coupling; Input range 0÷400 pC; Resolution 12 bit)
This system provides an easy solution to improve the TRD
identification capability: the number of straw tubes per module over
the threshold will be counted (i.e. the number of TR photons absorbed
in different straw tube counters). A Monte Carlo analysis is planned to
study and to verify the TRD PID performance with this solution.
Nicola Mazziotta, Dec. 6, 2005
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TRD work progress in Bari
Nicola Mazziotta, Dec. 6, 2005
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PS beam line PID strategy (TBR)
1. Electron: C1 • C2 • TRD, in whole momentum range, Cerenkov gas
pressure to select electrons
2. Hadron: (C1 + C2 + TRD), from 2 GeV/c, Cerenkov gas pressure to
select electrons and muons
3. Proton: (C1 + C2 + TRD), from 12 GeV/c, Cerenkov gas pressure
to select kaons
4. Muons: beam off, in whole momentum range
A more detailed analysis need to be performed in order
to define the correct strategy for particle identification
and to evaluate the efficiency and the contamination.
Nicola Mazziotta, Dec. 6, 2005
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SPS North area H4 beam
• 10 - 400 GeV/c, up to 108 particles/spill (π+)
• H4 can be set-up for very clean electron beam (up to ~300 GeV/c)
• H2/H4 originate from same (T2) target
– due to beam optics, H2 and H4 should run with opposite polaritiy
beams
– e.g. H2: protons or π+, H4: electrons
– beam conditions of H2 and H4 users need to be coordinated
• provision of (threshold) Čerenkov counter(s)
– usally 1 counter available per beam line, 2 can be requested
– also more sophisticated differential Čerenkov counters (CEDAR)
available at SPS (but tricky to commission and to operate, only on
STRONG request)
Nicola Mazziotta, Dec. 6, 2005
23
Particle Production at the Primary H4 Target (T4)
1.Using the simulation tool
Geant3, the particle production
at T4 was simulated assuming a
primary proton beam of 400
GeV/c.
2.The target consists of a
Beryllium plate with a length of
30 cm (hy=2mm, bx=16mm).
3.Production rates are simulated
within the limits of ±0.1mm and
±12(2)mrad.
4.The total number of simulated
protons on target (pot) is 108
Nicola Mazziotta, Dec. 6, 2005
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Negative Particles at SPS H4 line with T4 target
Nicola Mazziotta, Dec. 6, 2005
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T2 target wobbling (1)
The "democratic" wobbling centers the beam between H2 and H4 on the TAX
and the two beamlines get the same momentum with opposite signe at an
production angle of 0 mrad.
Nicola Mazziotta, Dec. 6, 2005
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T2 target wobbling (2)
Another very often used wobble scheme is to turn B1T and B2T off,
such that the 0mrad production angle is pointing towards H4, which
allows to provide a high electron intensity there. H4 is delivered with
charged particles by using B3T.
Nicola Mazziotta, Dec. 6, 2005
27
TRD threshold and saturation values
• The TR threshold (gth) depends on the foil thickness
(d1) and on its plasma frequency (ω1)
• The TR saturation (gsat) depends on the gth value and
on the foil gap (d2)
– gth = 2.5 d1(μm) ω1(eV)
– gsat  gth (d2/d1)1/2
gth
gsat
240
420
 3000
50
500
2625
 8000
50
500
3050
 9500
Material
ω1(eV)
C-fibres
28
6
Polyethylene
21
Mylar
24.4
Nicola Mazziotta, Dec. 6, 2005
d1(μm) d2(μm)
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Particle identification at SPS H4 line
• The Cherenkov (differential and threshold)
counters can be used to tag the hadrons
and to identify the electrons
• The Fast-TRD allows the electron/hadron
identification up to few 100 (400) GeV/c
• The Fast-TRD allows the pion/proton
identification from few 100 GeV/c to 1
TeV/c
• The TOF systems can be also used to tag
hadrons in the beam
Nicola Mazziotta, Dec. 6, 2005
29