Preliminary study of electron/hadron discrimination with the NEUCAL detector Lorenzo Bonechi University and INFN – Florence (Italy) 11th ICATPP - Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications 5-9 October 2009, Villa Olmo (Co), Italy

The NEUCAL working group O. Adriani 1,2, L. Bonechi 1,2, M. Bongi 2, S. Bottai 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 2ICATPP Lorenzo Bonechi5 October 2009

Outline of this presentation Basic ideas – e/hadrons discrimination with e.m. calorimeters – Use of neutron detectors (PAMELA experiment) – The new NEUCAL concept Simulations The prototype detector – Description of apparatus and assembling Test beam at CERN SPS (August 2009) – Event show and first preliminary comparison with the GEANT4 simulation 3ICATPP Lorenzo Bonechi5 October 2009

PART 1 5 October 2009ICATPP Lorenzo Bonechi4 Basic ideas

e/hadrons discrimination in HEP Common requirement for HEP experiments – particularly important for those devoted to Astroparticle Physics Electromagnetic calorimeters – very good discrimination capability in a wide energy range 5 October 2009ICATPP Lorenzo Bonechi5 18 GeV/c electron 36 GeV/c proton Two events detected by the PAMELA space experiment SILICON TRACKER MAGNET TRIG. SCINTI. E.M. CALO

The situation at higher energy Interacting protons with energy beyond few hundreds GeV can be tagged as electrons due to – similar energy release in calorimeter than electrons – similar shower development than electrons It is not possible, especially for space experiments, to increase too much the calorimeter depth – strong limitation in weight and power consumption Complementary detectors, like trackers, cannot help easily at these energies 5 October 2009ICATPP Lorenzo Bonechi6

The use of a neutron counter in PAMELA Neutron production Neutron production: – Protons: nuclear excitation, hadronic interaction and Giant Resonance – Electrons: only through the Giant Resonance Different yield in neutron Different yield in neutron production are expected for e.m. or hadronic showers New idea in PAMELA New idea in PAMELA: use a neutron counter as the final stage of the apparatus (beyond calorimeter) 5 October 2009ICATPP Lorenzo Bonechi7 18 GeV/c electron 36 GeV/c proton

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) 5 October 2009ICATPP Lorenzo Bonechi8 SCINT PMT or Si-PMT 3 He tube n

PART 2 5 October 2009ICATPP Lorenzo Bonechi9 Simulation

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 5 October 2009 ICATPP Lorenzo Bonechi scintillator layers 3 He Tubes (1 cm diam.) 30 X 0 NEUCAL BGO tiles

Distribution of number of neutrons 5 October 2009ICATPP Lorenzo Bonechi GeV electrons 1 TeV protons Note: energy release inside the BGO calorimeter is almost the same for 1TeV protons and 400 GeV electrons. FLUKA

Scatter plot: arrival time vs neutron energy 5 October 2009ICATPP Lorenzo Bonechi12 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

Expected performance (comparison FLUKA/GEANT4) 5 October 2009ICATPP Lorenzo Bonechi13 FLUKA simulated energy release inside one scintillator layer See also: S.Bottai et al., at Frontier Detector for Frontier Physics, La Biodola (Elba), May 2009 Neutrons up to few MeV kinetic energy are moderated and detected with high efficiency. At 10 MeV 70% of neutrons gives detectable signals. Only 10% are fully moderated to be detectable by the 3 He Tubes 1 MeV neutrons 10 MeV neutrons ENTRIES

PART 3 5 October 2009ICATPP Lorenzo Bonechi14 The prototype detector

Production of scintillators 5 October 2009ICATPP Lorenzo Bonechi15 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 5 October 2009ICATPP Lorenzo Bonechi16 Saint Gobain BC-630 Optical grease: Saint Gobain BC-630 PMT Hamamatsu R5946

Production of the first module 5 October 2009ICATPP Lorenzo Bonechi17 Canberra 12NH25/1 3 He proportional counter tube: Canberra 12NH25/1 1 cm diameter

Prototype assembly 5 October 2009ICATPP Lorenzo Bonechi18 3x3 matrix of scintillator modules with 5 3 He proportional counter tubes integrated 1 cm diameter 3 He tubes scintillator light guide PMT

Digitalization electronics 5 October 2009ICATPP Lorenzo Bonechi19 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 )

PART 4 5 October 2009ICATPP Lorenzo Bonechi20 Test beam at CERN SPS (August 2009)

Integration of the NEUCAL prototype with a 16 X 0 tungsten calorimeter (25 July 2009) 5 October 2009ICATPP Lorenzo Bonechi21 NEUCAL CALORIMETER

5 October 2009ICATPP Lorenzo Bonechi22 CALORIMETER

Beam test details 5 October 2009ICATPP Lorenzo Bonechi23 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 5 October 2009ICATPP Lorenzo Bonechi24 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? 5 October 2009ICATPP Lorenzo Bonechi25 Trigger Prompt signal Scint. A Particle signal t=0t=1ms Prompt signal t  10us Scint. B Particle signal ? time

Digitalization of one muon event 5 October 2009ICATPP Lorenzo Bonechi26 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)

Digitalization of one electron event 5 October 2009ICATPP Lorenzo Bonechi27 Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals All signals rise at t = 0 (prompt shower secondaries)

Digitalization of pion events (1) 5 October 2009ICATPP Lorenzo Bonechi28 Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t ~34  s t ~100  s

Digitalization of pion events (2) 5 October 2009ICATPP Lorenzo Bonechi29 Scintillators 3He tubes DOWNSTREAM UPSTREAM Trigger signals t ~28.5  s t ~46.8  s t ~250  s

Digitalization of pion events (3) 5 October 2009ICATPP Lorenzo Bonechi30 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 5 October 2009ICATPP Lorenzo Bonechi events - “single” signals - one single central PMT GEANT4 data Instrumental effect ? Spurious particles ENERGY ARRIVAL TIME 100 GeV ELECTRONS

First preliminary comparison data/MC 5 October 2009ICATPP Lorenzo Bonechi events - “single” signals - one single central PMT GEANT4 data Spurious particles ? ENERGY ARRIVAL TIME 350 GeV PIONS

Comparison data/MC: signal energy distribution 5 October 2009ICATPP Lorenzo Bonechi ELECTRON events PION events GEANT4 PRELIMINARY

Comparison data/MC: time distribution 5 October 2009ICATPP Lorenzo Bonechi ELECTRON events PION events GEANT4 PRELIMINARY

Conclusions A new neutron detector, NEUCAL, is under study for particle identification purposes Its aim is to help e.m. calorimeters in e/hadron separation at H.E. New idea: use an active moderator (plastic scintillator) to moderate the neutrons and detect their signals simoultaneously A prototype has been developed e tested with charged particles during a beam test at CERN SPS (August 2009) First very preliminary comparison between data and GEANT4 simulation shows substantial agreement, even if some effects is not yet understood (instrumental effect?) 35ICATPP Lorenzo Bonechi5 October 2009

Backup slides 5-9 October 2009ICATPP Lorenzo Bonechi36

Expected performance 5 October 2009ICATPP Lorenzo Bonechi37 Simulated energy release inside NEUCAL (12 scintillator layers detector) S.Bottai et al., at Frontier Detector for Frontier Physics, La Biodola (Elba), May 2009 Neutrons up to few MeV kinetic energy are moderated and detected with high efficiency. At 10 MeV 70% of neutrons gives detectable signals. Only 10% are fully moderated to be detectable by the 3 He Tubes

Filter 5-9 October 2009ICATPP Lorenzo Bonechi38