NUSTAR Week - 2013, Helsinki (Finland)

(7-11 October 2013)

Status of BELEN detector

Guillem Cortes Rossell

October 11th, 2013

E-mail: guillem.cortes@upc.edu

http://greener.upc.edu/greter

BELEN detector configuration

Polyethylene shielding

Beam hole

Front view

• Energy of beta-delayed neutrons not well known

• The neutron detection efficiency must be as flat as

possible for a wide range of neutron energies

• The efficiency depends on many parameters:

• Diameter of beam hole

• Number of neutron counters

• Distance of counters to the center of polyethylene

matrix

• Number of rings

Rings of 3He proportional counters Polyethylene matrix

3-D view

Neutron detection efficiency

• Number of rings

We need to find

the optimal

configuration

MC simulations

Neutron source

Point source

Inside the beam hole

Centered in the matrix

Neutrons emitted in all directions

(isotropic distribution)

Simulation codes

MCNPX 2.5

GEANT4

Neutron energies simulated

0.0001 MeV

0.001 MeV

0.01 MeV

0.1 MeV

1 MeV

2 MeV

3 MeV

4 MeV

5 MeV

Polyethylene properties

Density: 0.95 g/cm3

HD-Polyethylene (HDPE)

CH2

MC Simulations

Parameter used to define the planarity of neutron detection efficiency

Efficiency factor, F: The relation between the maximum efficiency, ηmax,

and the minimum efficiency, ηmin ,at a defined

interval of neutron energies

max

η

η=F η1,min η1,max

minηη1,min η1,max

Neutron energy interval : 10 keV – 2 MeV

048.11.60

0.63

min,1

max,1

1 ===η

ηF

Example

Detector Name

3He counters

Pressure (atm) ExperimentRatio

@2 MeV

Ratio @

5 MeV

Mean efficiency

Beam hole radii (cm)

BELEN-20 20 20 IGISOL: Jyväskylä - 2009 --- DONE 1.17 [1.60] 27% 5.5

BELEN-20 20 20 IGISOL: Jyväskylä - 2010 --- DONE 1.17 [1.60] 35% 5.5

BELEN-30 20+10 20 & 10 GSI: Germany – 2011 --- DONE 1.17 [1.70] 40 %11.5

(SIMBA)

BELEN-48 40+8 8 & 10PTB: Germany-2013 (Detector

calibration) --- DONE1.02 1.16 45% 5.5

BELEN-48 40+8 8 & 10 IGISOL: Jyväskylä - 2014 --- Approved 1.02 1.16 45% 5.5

EXPERIMENTS WITH BELEN PROTOTYPES

3 prototypes constructed : B ELEN-20, BELEN-30 and BELEN-48

[1]

[2]

[3]

[4]

[5]

[1] Submitted (july-2013) a paper to Nuclear Inst. and Methods in Physics Research, A: M.B. Gómez et al.“Design

and commissioning of the BEta DeLayEd Neutron detector”

[2] Not yet finished data analysis. Distribution of neutron counters optimized to increase the mean efficiency.

[3] GSI: S410/S323. “Measurement of beta-delayed neutrons around 3rd r-process peak”. Data analysis will be

finished first semester 2014. Phd.Thesis Roger Caballero

[4] Measurements done on 24-28 June 2013. Preliminary experimental results agree with MC simulations

[5] The experiment “Measurement of the beta-delayed 2-neutron emitter 136Sb”is approved and scheduled for first

semester 2014. Two matrix will be used: One with a beam hole of 3 cm radii, and other with a beam hole radii of

5.5 cm to insert a HPGe detector for gamma coincidence measurements.

EXPERIMENTS WITH BELEN PROTOTYPES

B ELEN-20 B ELEN-30

Evolution of neutron detection efficiencies

B ELEN-48Beam hole 3 cm radii Beam hole 5.5 cm radii

OTHER EXPERIMENTS WITH A PROTOTYPE OF BELEN-SHAPED CONFIGURATIONS

Ring Radii (cm)Number of

counters

Pressure

(atm)

Diameter

(inch)Institute

1 12.0 10 10 2 ORNL

2 19.5 42 8 1 UPC

Example: Configuration for max. neutron energies of 3 MeV

• Design of a big BELEN detector for the measurement of beta-delayed 1-neutron and 2-

neutron emission at RIKEN (BRIKEN collaboration).

• Not yet submitted the proposal (expected april-2014)

• Measurements (if approved) at RIKEN: end of 2014 or beginning 2015

Neutron detection efficiency

2 19.5 42 8 1 UPC

3 25.0 10+13x2+15 8/5.13/4 1/1.18 GSI+RIKEN+JINR

4 30.5 22 10 2 ORNL

5 36.0 24 10 2 ORNL

149 3He

counters

Front view of the

polyethylene

matrix

CONSTRUCTION STATUS OF THE BELEN DETECTOR FOR FAIR

Equipment available

- 52 3He neutron counters: The neutron detector designed consists on 48 counters (40 from UPC and 8 from GSI) the other 4 counters are reserved for

replacement if needed. See table 1

- Matrix: (900 mm x 900 mm x 800 mm) block of high density polyethylene (density = 0.95 g/cm3) for the BELEN-48 prototype

(11 cm beam hole)

- Electronics: 2 crates, ADC’s 8 channels/ADC, shapers, HV sources, clock & pulse generator, pre-amplifiers

Equipment/material pending

- Matrix: (900 mm x 900 mm x 800 mm) block of high density polyethylene (density = 0.95 g/cm3). See table 2

- Wiring + connectors

- Supporting table

Units in mm Central holeRings

Inner Central Outer

Diameter 160 110 170 210

Holes diameter -- 27.5 27.5 27.5

Number of 3He counters at 10 atm -- 0 8 0

Number of 3He counters at 8 atm -- 10 4 26

Diameter

(cm)

Effective

Length

(inch/mm)

GSI He-3 10 2.54 600 10

UPC He-3 8 2.54 600 42

52

NUMBER OF

COUNTERS

TOTAL

INSTITUTEFILLING

GAS

PRESSURE

(atm)

DIMENSIONS

Table 1. Properties of neutron counters Table 2. Dimensions of polyethylene matrix BELEN-48

- Supporting table

CONSTRUCTION STATUS OF THE BELEN DETECTOR FOR FAIR

Front view of the detector with a

beam hole of 16 cm diameter

Neutron detection efficiency for BELEN-48

(16 cm diameter beam hole)

BELEN-48 + AIDA

To be done

- Test the possibility to modify the cross section of beam hole by a squared cross section to fit better

AIDA

- New designs to optimize he efficiency for different neutron energy ranges (optional)

- Design a table to move the detector (distance from centre of beam line to the ground needed)

- Explore the possibility to use more counters to increase the efficiency (Dubna?)

FUNDING STATUS

Research Institution Funding institution EquipmentINVESTED

(kEUR)

REMAINING

[until 2015]

(kEUR)

42 He-3 neutron counters (1) 154 (2)

Electronics + Polyethylene 111

Electronics + Polyethylene + Support structure 30

10 He-3 neutron counters + Polyethylene+Electronics 140

Polyethylene+Electronics 25

Total 301 55

TOTAL COST OF BELEN

Universitat Politècnica de Catalunya

Barcelona (Spain)

IFIC - Valencia (Spain)

356

Spain Government, Ministry of Economy

and Competitiveness, Plan Nacional de

I+D+I

Spain Government, Ministry of Economy

and Competitiveness, Plan Nacional de

I+D+I, FPA2011-28770-C03-03

GSI - Darmstadt (Germany)German Helmholtz Association via the

"Young Investigators Project VH-NG-627"

Electronics + development of software for DACQ system 50

(1) The 3He pressure of first 22 neutron counters was 20 atm.

• To increase the efficiency we needed to increase the number on neutron counters

• 2 options:

– Buy 20 new counters: Too expensive (aprox. 20 kEUR/counter )

or

– Duplicate the 21 neutron counters reducing the pressure to 8 atm and refill 21 new counters at 8 atm:

42 new counters at 8 atm (aprox. 3 kEUR/counter)

– One counter at 20 atm has been reserved for testing

(2) The price includes the cost of first 22 neutron counters and the cost related with the modification of 42

counters

MEMBERS OF THE COLLABORATION BUILDING THE DETECTOR

Research institution City and Country Members (Alphabetical order)

Universitat Politècnica de Catalunya Barcelona, Spain Roger Caballero, Francisco Calviño, Guillem Cortés(*)

, Carme Pretel, Albert Riego

Instituto de Física Corpuscular (IFIC), CSIC-Valencia, Spain

Jorge Agramunt, Alejandro Algora, César Domingo-Pardo, M. Dolores Jordan,

STATUS OF THE TDR

• The definitive version of the TDR will be submitted to the collaboration on January-2014 to be approved

Includes:

- Optimized neutron counter distribution in PE matrix (new results from prototypes)

- New 3He neutron counters at 8 atm

Instituto de Física Corpuscular (IFIC), CSIC-

Universidad de ValenciaValencia, Spain

Jorge Agramunt, Alejandro Algora, César Domingo-Pardo, M. Dolores Jordan,

Berta Rubio, José Luís Taín

CIEMAT Madrid, Spain Daniel Cano-Ott, Trino Martínez, Emilio Mendoza

GSI Darmstadt, Germany Iris Dillmann, Alexey Evdokimov, Michele Marta

(*) Spokesperson of BELEN detector