PID, trigger and DAQ for the GLAST beam test (preliminary study) Nicola Mazziotta INFN Bari [email protected] Dec. 6, 2005

PID, trigger and DAQ for the GLAST beam test

(preliminary study)

Nicola MazziottaINFN Bari

[email protected]. 6, 2005

Nicola Mazziotta, Dec. 6, 2005 2

Scope

Particle identification and trigger layout to be used in the PS and SPS beam test

Cerenkov


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


PS Particle type and intensityElectrons, 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 %


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

• Proton below the Cerenkov threshold up to 16 GeV/c


Electron tagging with threshold Cerenkov counters

PS T9 Beam C1 (CO2) 5 m long C2 (CO2) 3 m long

Electrons = C1 * C2

C1 and C2 are threshold Cerenkov counters filled with CO2, for each energy the CO2 pressure has been set to select the Electrons


Electron tagging by threshold Cerenkovs

BeamC1 (CO2) 5 m long C2 (CO2) 3 m long

EM CAL

Electrons

Pions-

con

tam

inat

ion

1.2

%

Pion contamination in the electron sample is few %

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


Hadron tagging with threshold Cerenkov counters


Hadrons = (C1 + C2),

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)

Electron/Muon contamination in the hadron sample = (1- 1) (1-2) fe/f (< 10-3 from 3 to 6 GeV/c).


Proton tagging with threshold Cerenkov counters


Protons = (C1 + C2)

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

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).


HARP Proton tagging by Cerenkov counters

PS T9 Beam C1 (N2) 5 m long C2 (N2) 3 m long


Hadron tagging by TOF system

m1, m2, p L

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

0 1 2 3 4 5 6 7 8 9 10

Beam momentum (GeV/c)

Delt

a T

OF

(n

s)

Proton/Kaon Kaon/Pion Pion/Muon

Muon/Electron Pion/Electron 3 sigma resolution

L = 10 m, sigma = 100 ps


Observed particle fractions in the T9 beam by HARP experiment (L=21.4 m)

proton contamination in positron sample


PS T9 beam area

5 m

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


Electron/Hadron idetification by TRD

Particle ID is based on the threshold properties of the TRsat

th

Electron/pion identification: 1-100 GeV

Pion/proton identification: few 100 GeV - 1 TeV


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


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)


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


Fast-TRD for SPS-beam: trigger layout

to TRIGGERor

to VETO

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


Fast-TRD: e/ beam

e/ ~ GeV/c /p ~ 100 GeV/c

e vs as trigger vs e as veto

ee

For more details see NIM A 455 (2000) 305

pions contamination about 1 % @ 90% electron efficiency


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.


TRD work progress in Bari


PS beam line PID strategy (TBR)

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.

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


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)


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


Negative Particles at SPS H4 line with T4 target


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.


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.


TRD threshold and saturation values

• The TR threshold (th) depends on the foil thickness (d1) and on its plasma frequency (ω1)

• The TR saturation (sat) depends on the th value and on the foil gap (d2)

th = 2.5 d1(μm) ω1(eV)

sat th (d2/d1)1/2

Material ω1(eV) d1(μm) d2(μm) th sat

C-fibres 28 6 240 420 3000

Polyethylene 21 50 500 2625 8000

Mylar 24.4 50 500 3050 9500


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

Documents

PID, trigger and DAQ for the GLAST beam test (preliminary study) Nicola Mazziotta INFN Bari [email protected] Dec. 6, 2005