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

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 – signals due to absorption of neutrons by 3 He (proportional tubes) 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 = MeV) SCINT PMT or Si-PMT 3 He tube n

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

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), May MeV neutrons 10 MeV neutrons ENTRIES

3 He Tubes

Distribution of number of neutrons in real e-h showers 400 GeV electrons 1 TeV protons Note: energy release inside the simulated BGO calorimeter is almost the same for 1TeV protons and 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 Outgoing neutron energy Log ( E(GeV)/1GeV ) Arrival time (seconds) 1 GeV1 MeV 100 ns 1  s 1 keV 10 ns

The prototype detector

Production of scintillators One side covered with aluminized tape Scintillator material: Eljen Technology, type EJ-230 ( PVT, equivalent to BC-408 ) Light guides: simple plexiglas

Production of prototype detecting modules Saint Gobain BC-630 Optical grease: Saint Gobain BC-630 PMT Hamamatsu R5946

Production of the first module Canberra 12NH25/1 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 scintillator light guide PMT

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) NEUCAL CALORIMETER

Beam test details CERN SPSH4 CERN SPS, line H4 (one week test) Beam type – energy - # of events: – Pions – Pions350 GeV( events) – electrons – electrons100 GeV( events) – electrons – electrons150 GeV( events) – muons – muons150 GeV( 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…)

Next slides report a comparison of data with GEANT4 simul. for electron and pion events taken in the following configurations: Detectors’ configuration ELECTRON beam PION beam Total thickness upstream NEUCAL: 16 X 0 Total thickness upstream NEUCAL: (16+13) X 0 NEU CAL 16 X 0 W CALO NEU CAL 16 X 0 W CALO 9 X 0 Pb 2.25 X 0 PbWO 4` 30 

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 How to find neutron signals? Trigger Prompt signal Scint. A Particle signal t=0t=1ms Prompt signal t  10us Scint. B Particle signal ? time

Digitalization of one muon event Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t = 0 t ~700ns Bounces are due to additional filters on the digitizer inputs to solve a problem of firmware (loss of fast signals)

Filter

Digitalization of one electron event Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals All signals rise at t = 0 (prompt shower secondaries)

Digitalization of pion events (1) Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t ~34  s t ~100  s

Digitalization of pion events (2) Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t ~28.5  s t ~46.8  s t ~250  s

Digitalization of pion events (3) Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t ~14.6  s t ~170  s t ~12.6  s t ~250  s

First preliminary comparison data/MC events - “single” signals - one single central PMT GEANT4 data Instrumental effect ? Spurious particles ENERGY ARRIVAL TIME 100 GeV ELECTRONS Specific MC to take into account the meterial in front of NEUCAL

First preliminary comparison data/MC events - “single” signals - one single central PMT GEANT4 data Spurious particles ? ENERGY ARRIVAL TIME 350 GeV PIONS

Comparison data/MC: signal energy distribution ELECTRON events PION events GEANT4 PRELIMINARY

Comparison data/MC: time distribution ELECTRON events PION events GEANT4 PRELIMINARY

Test at NTOF facility Proton beam Target ~ 200 meters Neucal Very intense p beam (20 GeV, 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 2 weeks at end of October Many thanks to the NTOF collaboration!!!!! Neutrons

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!!!!!!!!!