Preliminary study of electron/hadron discrimination with the NEUCAL detector

The NEUCAL working group

O. Adriani

1,2 , L. Bonechi 1,2 , M. Bongi

2 , S. Bottai 2 , M. Calamai

4,2

, G. Castellini

3 , R. D’Alessandro 1,2 ,

M. Grandi

2 , P. Papini 2 ,

S. Ricciarini

2 , G. Sguazzoni 2 , G. Sorichetti 1 , P. Sona 1,2 ,

P. Spillantini

1,2 , E. Vannuccini 2 , A. Viciani 2

1) University of Florence 2) INFN Section of Florence 3) IFAC – CNR, Florence 4) University of Siena

• •

Detection of neutrons produced inside the calorimeter: the NEUCAL concept PAMELA:

Moderation of neutrons by means of passive moderator (

polyethylene

layers)

3 He proportional tubes

to absorb thermal neutrons and detect signals due to the ionization of products inside gas n + 3 He  3 H + p (Q = 0.764 MeV) • • • New idea in NEUCAL: Study of the

moderation phase

using an

active moderator

Standard

plastic scintillators

are rich in hydrogen and then suitable as moderators ( Eljen EJ-230  [ CH 2 CH(C 6 H 4 CH 3 ) ] n ) Detection of: – signals due to neutron elastic/inelastic scattering –

n

3 signals due to absorption of neutrons by He (proportional tubes)

PMT or Si-PMT SCINT 3 He tube

Few details and results

• • First results based on FLUKA, now implementing also GEANT4 simulation Detector geometry has been dimensioned for application together with a 30 X 0 – calorimeter (CALET experiment) NEUCAL is placed downstream a  30 X 0 deep homogeneous BGO calorimeter

BGO tiles 11 scintillator layers 30 X 0 NEUCAL 3 He Tubes (1 cm diam.)

11 cm of plastic scintillators FLUKA based simulation Degree Thesis by G. Sorichetti

Expected performance (comparison FLUKA/GEANT4) FLUKA simulated energy release inside one scintillator layer See also: S.Bottai

et al

., at

Frontier Detector for Frontier Physics

, La Biodola (Elba), 24-30 May 2009

1 MeV neutrons 10 MeV neutrons

3 He Tubes

Distribution of number of neutrons in real e-h showers

Note: energy release inside the simulated BGO calorimeter is almost the same for 1TeV protons and 400 GeV electrons.

1 TeV protons

FLUKA

400 GeV electrons

FLUKA

Scatter plot: arrival time

vs

neutron energy

Almost all neutrons exit from the calorimeter within a few microseconds, but thermalization inside neucal can take hundreds microseconds

1



s 100 ns 10 ns Outgoing neutron energy Log ( E(GeV)/1GeV )

The prototype detector

Production of scintillators

Scintillator material:

Eljen Technology

, type EJ-230 ( PVT , equivalent to BC-408 ) Light guides: simple plexiglas One side covered with

aluminized tape

Production of prototype detecting modules PMT

Hamamatsu R5946

Optical grease

: Saint Gobain BC-630

Production of the first module 3 He proportional counter tube

: Canberra 12NH25/1 1 cm diameter

Prototype assembly

3x3 matrix of scintillator modules with 5 3He proportional counter tubes integrated

1 cm diameter 3 He tubes PMT light guide scintillator

Digitalization electronics CAEN V1731 board

 VME standard  8 ch, 500MS/s   8 bit ADC 2MB/ch memory (few ms digitization)   16 ns jitter On-board data compression ( Zero Suppression Encoding )

CAEN V1720 board

 VME standard  8 ch, 250MS/s   12 bit ADC 2MB/ch memory (few ms digitization)   32 ns jitter On-board data compression ( Zero Suppression Encoding )

Test beam at CERN SPS

(August 2009)

Integration of the NEUCAL prototype with a 16 X 0 tungsten calorimeter (25 July 2009)

CALORIMETER NEUCAL

CALORIMETER

Beam test details

• • • CERN SPS, line H4 (one week test) Beam type – energy - # of events: –

Pions

350 GeV ( 230000 events) –

electrons

100 GeV ( 240000 events) –

electrons

150 GeV ( 50000 events) –

muons

150 GeV (130000 events) Data collected in different configurations – scan of detector (beam impact point) – different working parameters • • PMTs and tubes voltages Digitizer boards parameters (thresholds, data compression…)

Detectors’ configuration

• Next slides report a comparison of data with GEANT4 simul. for electron and pion events taken in the following configurations:

NEU CAL 16 X 0 W CALO ELECTRON

beam Total thickness upstream NEUCAL:

16 X 0 NEU CAL 16 X 0 W CALO 30

 Total thickness upstream NEUCAL:

(16+13) X 0 PION

beam

How to find neutron signals?

• • Digitalization of scint. output for a long time interval (  1ms) Look for signals which are not in time with other signals on other channels: – Avoid the prompt signals due to charged particles coming directly from the shower – Avoid single charged particles giving signals on more then one scintillator (non interacting hadrons entering the detector Trigger

Scint.

A

Prompt signal Particle signal

?

time

Prompt signal Particle signal

Scint.

B t=0 t



10us t=1ms time

Digitalization of one muon event

Trigger signals UPSTREAM t ~700ns 1 2 3 t = 0 DOWNSTREAM Scintillators 4 5

Bounces are due to additional filters on the digitizer inputs to solve a problem of firmware (loss of fast signals)

3He tubes

Filter

Digitalization of one electron event

Trigger signals UPSTREAM All signals rise at t = 0 (prompt shower secondaries) DOWNSTREAM Scintillators 1 2 3 4 5 3He tubes

Digitalization of pion events (1)

Trigger signals UPSTREAM DOWNSTREAM Scintillators 1 2 4 t ~34



s 5 t ~100



s 3 3He tubes

Digitalization of pion events (2)

Trigger signals UPSTREAM DOWNSTREAM Scintillators 1 t ~28.5



s 4 5 2 3 t ~46.8



s t ~250



s 3He tubes

Digitalization of pion events (3)

Trigger signals UPSTREAM t ~14.6



s t ~170



s t ~12.6



s DOWNSTREAM Scintillators 1 4 2 t ~250



s 5 3 3He tubes

First preliminary comparison data/MC

100 GeV ELECTRONS Instrumental effect ?

33000 events “single” signals -

one single central PMT

GEANT4 data

Spurious particles ARRIVAL TIME

Specific MC to take into account the meterial in front of NEUCAL

First preliminary comparison data/MC

350 GeV PIONS ?

75000 events “single” signals -

one single central PMT

GEANT4 data

Spurious particles ARRIVAL TIME

Comparison data/MC: signal energy distribution

33000 ELECTRON events

GEANT4

75000 PION events

GEANT4

Comparison data/MC: time distribution

33000 ELECTRON events

GEANT4

75000 PION events

GEANT4

Test at NTOF facility

2 weeks at end of October Many thanks to the NTOF collaboration!!!!!

Proton beam Target Neutrons Neucal ~ 200 meters Very intense p beam (20 GeV, 10 12 p per spill) …But with very short spill (5 ns) …And very small duty cycle (5 ns/few ms) Neutrons are produced in the target with different energies Neutrons travel along the 200 m line The energy of the neutron is inferred from the arrival time on the Neucal detector

Signals on scintillators

Signals on 3 He

Basic Idea

• • By knowing the neutron spectrum (both in shape and absolute normalization) we can measure the single neutron efficiency as function of the neutron energy Analysis is complex!!!!!!!!!