NEDA (NEutron Detector Array) J.J. Valiente Dobon (LNL-INFN) on behalf of the NEDA collaboration.

NEDA (NEutron Detector Array)

J.J. Valiente Dobon (LNL-INFN)

on behalf of the NEDA collaboration

Organization

Spokeperson: J.J. Valiente Dobon (LNL-INFN)

GANIL Liason: M. Tripon (GANIL)

Steering committee:

-B. Wadsworth (U. of York)

-N. Erduram (U. of Istanbul)

-L. Sttugge (IRES – Strasbodurg)

-J. Nyberg (U. of Uppsala)

-M. Palacz (U. of Warsaw)

-A. Gadea (IFIC - Valencia)

Members of the collaboration:

U. of Ankara (Turkey), COPIN (Poland), CSIC-IFIC (Spain), Daresbury Laboratory (U.K.), GANIL (France), U. of Istanbul (Turkey), INFN (Italy), IRES (France), U. of Nidge (Turkey), U. of Uppsala (Sweeden), U. of York (U.K.) and Kolkata, India (under discussion)

FP7-INFRASTRUCTURES-2007-1

SPIRAL2 PREPARATORY PHASE

Working groups

•Detector characteristics (Physics interests of NEDA to define the detector specifications).

•Responsible: B. Wadsworth•Geometry (Make a full study of geometry to determine (materials) efficiency, reduce cross-talk, ... Comparison between different codes: Geant4, MCNP-X. Simulate effect of other ancillaries, neutron scattering.).

•Responsible: M. Palacz•Study New Materials (Exploring new materials, solid scintillators, deuterated liquid scintillators).

•Responsible: L. Stuttgé•Digital Electronics (Flash ADCs, GTS, EXOGAM2 electronics, ..)

•Responsible: A. Gadea•PSA (Pulse shapes analysis, PSA algorithms, ...).

•Responsible: J. Nyberg•Synergies other detectors (Detectors that can be considered in synergy with NEDA: EXOGAM2, PARIS, AGATA, FAZIA, GASPARD, DIAMANT, DESCANT, Neutron spectroscopy at DESIR, DESPEC/HISPEC, NEUTROMANIA, ... ).

•Responsible: P. Bednarczyk

Physics with NEDA

• Nuclear Structure– Probe of the T=0 correlations in N=Z nuclei: The structure beyond 92Pd

(Uppsala, LNL, GANIL, Stockholm, York)– Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states

(Warsaw, LNL, GANIL, York)– Coulomb Energy Differences and Nuclear Shapes (York, Padova, GANIL)– Low-lying collective modes in proton rich nuclei (Valencia, Istanbul, Milano, LNL,

Krakow)• Nuclear Astrophysics

– Element abundances in the Inhomogeneous Big Bang Model (Weizmann, Soreq, GANIL)

– Isospin effects on the symmetry energy and stellar collapse (Naples, Debrecen, LNL, Florence)

• Nuclear Reactions– Level densities of neutron-rich nuclei (Naples, LNL, Florence)– Fission dynamics of neutron-rich intermediate fissility systems (Naples,

Debrecen, LNL, GANIL)

NEDA will address the physics of neutron-rich as well as neutron deficient nuclei, mainly in conjunction with gamma-ray detectors arrays like AGATA, EXOGAM2, GALILEO and PARIS.

AGATA: A. GadeaEXOGAM2: G. de FranceGALILEO: C. UrPARIS: D. Jenkins

AGATA: A. GadeaEXOGAM2: G. de FranceGALILEO: C. UrPARIS: D. Jenkins

First day experiment

Nuclear structure N=Z beyond 92Pd : 96Cd, etc

AGATA/EXOGAM2 + NEDA

Low-lying collective modes in proton rich nuclei

Second day experiment

Transition densities

PARIS + NEDA

N=20

NEDA+PARIS experiment

34Ar + 16O → 44Cr + 2n (34Ar 108 pps)

The reaction to study the Pigmy resonance in 44Cr

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Physics themes

• G de Angelis – Physics with NEDA• G. de France - Results on the 92Pd experiment • A. Gottardo - Study of proton-rich nuclei with NEDA around A=100 • A. Pipidis - NEDA: At the service of n-p correlations • M. Palacz - Spectroscopy next to 100Sn: 3n gating and where is

100In? • A. Di Nitto – The role of isospin in fusion-evaporation reactions• G. Verde - The Farcos project and access to the symmetry energy

with proton-neutron measurements

-NEDA: Neutron detector to be used coupled to AGATA/EXOGAM2/GALILEO/PARIS

-Previous experience with the NWall (BC501) currently at GANIL

-High efficiency 25% for one neutron.

-Relatively good gamma/neutron discrimination.

-Problems with cross talk.

-Low efficiency for 2n (1-2%).

-Analogic electronics.

Problem definition

Neutron Wall

Neutron Wall

Neutron Wall: N=Z-2

A. Gadea et al., PRL97, 152501 (2006)S. Lenzi et al., PRL87, 122501 (2001)

24Mg(32S,2n)54Ni28Si(28Si,2nα)50Fe

Cross talk – low 2n cross section

•High cross talk between neighboring detectors

•It is not possible to differenciate between 2n real events or just 1n scattered.

•Therefore neighbouring detectors are dismiss in the analysis and the efficiency decreases to 1-2%.

One aim of NEDA is to be able to distinguish between real 2n events and scattered neutrons → Increase of the 2n efficiency.

J. Ljungvall et al., NIMA528 471 (2004)

Possible to improve 2n efficiency using TOF among detectors

Strategy of NEDA

-Optimization of the geometry: unitary cell size, spherical, planar, zig-zag, granularity, distance, versatile.

-FEE: GTS integrated in the motherboard and FADC in a mezzanine. Fully compatible with AGATA, GALILEO and EXOGAM2

-Use of the TOF information in addition to the measured energy to disentangle the 1n scattered events from the real 2n channels

-Use of the deuterated scintillator BC537

-Pulse height seems to be proportional to incident neutron energy (reported by DESCANT collaboration)

-Provides another method of determinig neutron energy beyond TOF

-Can lead to a better discrimination of high multiplicity neutron events and scattered events.

-New solid scintillators Lawrence Livermore National Laboratory

BC501 vs. BC537 response

Courtesy of P. Garrett, University of Guelph.

BC537BC501A

En = 4.3 MeV

En = 2.5 MeV

BC501 BC537

DESCANT

Presented by P. GarrettPresented by P. Garrett

Solid scintillators for neutron detection

Simulations

Neutron HP model in G4.9.2.p01 (rel. March 2009) much improved comparing to earlier versions

Total cross sections and angular distributions for elastic scattering on p, d, and 12C reasonable

Correct (high energy) γ-ray lines produced Wrong kinematics (angular distributions?) in the

12C(n,α)9Be reaction. Important reactions still missing, like 12C(n,n’)3α

Existing defficiencies not significant in the <~10MeV energy range, which if interest for

NEDA

Presented by M. PalaczPresented by M. Palacz

Light output of liquid scintillator

•The light-output L is usually given in MeVee: the particle energy required to generate 1 MeVee of light is defined as 1 MeV for fast electrons •L is generally less for heavier particles such as protons, deuterons, alphas, beryllium, carbon…• Therefore, the light output L in a certain path dx is a function of the deposited energy E in dx: L(E)

Dekempeneer et Liskien NIM A 256 (1987) 489-498

Deposited energy Light output

Presented by A. GottardoPresented by A. Gottardo

Geometry study

Definition of the unitary cell dimensions

Presented by G. JaworskiPresented by G. Jaworski

Geometries

There are two possible main geometries, either spherical or planar.

•The spherical geometry presents the full symmetry.

•The planar has some advantages, than the spherical does not present.

-Flexibility – different arrangements of the detectors, e.g. zig-zag

-Different focal posistions (500cm, 1000cm, 2000cm)

-Budget issues

Performance of diff. geometries

Flat Zig-zag Spherical

BC501ABC537

Presented by T. HüyükPresented by T. Hüyük

Discriminating neutron/gamma

Pulse shapes from the detector differs between neutrons and gamma rays.

Usually both pulse shape analysis and the time-of-flight information is used for discrimination neutron-gamma discrimination.

neutrons

Digital electronics: PSA

It is possible to obtain better quality using same algorithms but digital electronics

Analog zero-crossover method

Applying an artificial neural network can increase the quality even further

Digital electronics: Neural Network

P=sqrt(εn2+εγ

2)

GTS supervisor

Event Builder

PSA

Pre-processing

Digitizer

TrackingOnline analysis

GTS local

prompt trigger

REQ

VAL

REQ

VAL

Global Merger

GA

MM

A-A

RR

AY

GTS local

Event Builder

PSA

Pre-processing

Digitizer

NE

DA

NEDA coupled to AGATA/EXOGAM2

ADC Logic- FADC samples collection- Digital Processing

- Trigger- Data formatting- Inspection control

PPC

Common Logic

GTS Fanin ADC Logic Interface

Clocks(Local &

Recovered)

Delay Line

OpticalLink

Flash (Linux)

SRAM(Oscilloscope)

PROM(VHDL)

PROM(VHDL)

DPRAM(Physics, ADONIS)

Ethernet 100

Ethernet Gigabit

PCIe(Adonis)

8*FADC14 bits

100MHz

DACs(Test, control,

inspection)

Seriallink

SDRAM

Mux

MGTClocks

Fast serial links

Parallel linksSlow control

Serial link

Digital electronics: EXOGAM2-NEDA

Basic diference EXOGAM2/NEDA is the ADC: 200-300 MHz 12-14bit

Presented by M. TriponPresented by M. Tripon

Silicon Photo multipliers readout

Direct replacement for photomultiplier tube

Insensitive to magnetic fields Can operate in vacuum Large sizes possible Attractive for simultaneous PET and

MRI scanning

SPMPlus

Synergy with PARIS – D. Jenkins

BC501A and BC537 detectors

Currently bought commercial detectors from Saint Gobain

•Two detectors 5”x5” BC537 (LNL-INFN)

•Two detectors 5”x5” BC501A (York-Valencia)

A. Pipidis (founded SP2PP) working on the characterization of the detectors.

Summary

• Currently bought BC537 and BC501A commercial detectors to test:

– cross talk – light production – FADC – frecuency and number of bits– PSA – neutron-gamma discrimination

• First contacts with Livermore – Start up collaboration solid scintillators?

• Test of SPMPlus from York in BC537 and BC501A • Development of electronics in synergy with EXOGAM2• Optimal geometry

Workshop program

Phases of NEDA

The current development on new materials and readout systems for neutron detection makes necessary to build NEDA in four different phases:

• Phase 0: Upgrade of Neutron Wall with digital electronics.• Phase 1: R&D on new material and light readout systems for a

highly segmented neutron detector array.• Phase 3: Construction of a limited size Demonstrator • Phase 4: Final construction of NEDA

With current technological status …

• Three main options:– 200 detectors BC501A – PM readout –Digital electronics

• Total cost: 600K€ (BC501A) + 200K€(Elec.) + 40K€ (mechanics) = 840 K€

– 200 detectors BC536 – PM readout – Digital electronics• Total cost: 2000K€ (BC537) + 200K€(Elec.) + 40K€ (mechanics) = 2240 K€

– Upgrade Neutron Wall - Phase 0 (Digital electronics)• Total cost (50 channels) = 40K€

Collaborating Institutes

• Centro Superior de Investigaciones Cientificas (CSIC) – Valencia• Grand Accelerateur National d’Ions Lourds (GANIL)• Istituto Nazionale di Fisica Nucleare – Laboratori Nazionale di

Legnaro• Royal Institute of Technology - KTH• University of Istanbul• University of Lund• University of Nidge• University of Uppsala• University of Warsaw• University of York

Summary and future work

• NEDA – Looks at improving efficiency for 2n channels – BC537, geometry• Validated simulatons – realistic results for BC501 and BC537• Included model for light production.• PSA algorithms to discriminate neutron-gamma – Neural Network great perspectives.• Synergies

– PARIS (A. Maj): SPMPlus, electronics?– EXOGAM (G. De France): electronics– Neutron Spectroscopy at DESIR (D. Cano & N. Orr): Simulations, FADC

FUTURE WORK• Currently bought BC537 and BC501 commercial detectors to test:

– cross talk – light production – PSA – neutron-gamma discrimination

• Test of SPMPlus from York in BC537 and BC501 • Development of electronics in synergy with EXOGAM2• Design of FADC mezzanines• Optimal geometry

NEDA possible geometries

Step-spherical Spherical

Neutron-γ discrimination

BC537 n-γ discrimination

BC501A(D) n-γ discrimination

Light output

Time scale

2008 2009 2010

Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3

Validation GEANT4 neutron simulations

Geometry definition

Digital algorithms for PSA

Detector prototype

Test prototype

Electronics

Negoziations MoU

MoU signature

Silicon PM

Synergies

EXOGAM array

PARIS

Commercial electronics: Struck

4 channel VME digitizer/transient recorder with a sampling rate of up to 500 MS/s (for the individual channel) and 12-bit resolution

Programmable FPGAs

Intrinsic efficiency of BC501A and BC537