Beta dELayEdNeutron (BELEN) detector...

NUSTAR ANNUAL MEETING - 2013

GSI Darmstadt, Germany

Beta dELayEd Neutron(BELEN) detector status

ROGER CABALLERO-FOLCHUniversitat Politècnica de Catalunya

26 de febrer de 2013

(BELEN) detector status

Detection system

Previous versions used at JYFL and GSI – Design and analysis/results status

Contents

Previous versions New designsDetection system

analysis/results status

New designs and conclusions

1

Detection system


Contents

Previous versions New designsDetection SystemDetection system



2

β delayed neutron emission


3

3He counters as detector

� The detection of the neutron is based on an indirect method: the detection

of the products of the reaction of the neutron with 3He counters:

3He + n �� 3H + 1H + 765 keV

Other reactions:

10B + n → 7Li* + 4He + 2310 keV

7Li* → 7Li + 480 keVnn

Polyethylene

moderator


Ion beam nProportional3He counter

Silicon

β decay detector

Counter Gas Maximum

length (mm)

Effective

length

(mm)

Maximum

diameter

(mm)

Effective

diameter

(mm)

Gas

pressure

(atm)

Cathode

material

2527

LND inc

3He 686.84 604.8 25.4 24.38 20 / 10 / 8

Stainless

Steel

4

Noise

Neutron signal

Electronic chain for data acquisition and signal processing


5

Analog system: Trigger

Digital system: Triggerless

Digital Data Acquisition System (DDAS)

J. Agramunt & IFIC team

The electronic chain of the

acquisition system

operates independently

of the other systems of the

experiment and detectors

along the beamline. It only

needs to synchronize the

timestamp.

Detection system


Contents

Previous versions New designsDetection system Previous versions

and analysis/results status


6

Tests and experiments with BELEN detector

GSI:S410 “Measurement of β-delayed neutrons around the 3rd r-process peak” C. Domingo-Pardo et al.PERFORMED, September 2011

GSI: S323 “Beta-decay of

very neutron-rich Rh, Pd,

Ag nuclei including the r-


7

Neutron number N

Ag nuclei including the r-

process waiting point 128Pd”. F. Montes et al.

PERFORMED,

September 2011

Z=28, N=50;

JYFL (2009, 2010 & 2013)I162 “Delayed neutron measurements for advanced reactor technologies and astrophysics” JL Taín JYFL. Expected 2013B.Gomez-Hornillos et al. NIM in progress (2009 exp)

Z=50, N=82

Background measurements at GSI (2010) and LSC Canfranc (2011) D.Jordan et al. Astr.Phys Vol.42, Feb 2013, p.1–6

Support structure requirements:

Hold and transport 650 Kg

Allow access to the beam hole

Movable in Z for fine placement

Table + tray movable on “z” on railsMoving tray

BELEN design for JYFL experiments


Polyethylene matrix hold together and

can be lifted as a single unit.

Polyethylene: 10 cm thick vertical

slices assembled => 90 x 90 x 80

cm3 ~650 Kg detector

Fixed support

8

JYFL experiment 2009 & 2010 - BELEN-20

20 3He counters at 20 atm

1ST ring: 8 counters at 11 & 9.5 cm

2nd ring: 12 counters at 20 & 14.5 cm

Average efficiency: 27% & 35% (5MeV)

Dimensions: 50x50x80 cm3 + shielding (90x90x80 cm3)

Diameter holes: 2.75 cm

Central hole radius: 5.5 cm


Central hole radius: 5.5 cm

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S410/S323 experiments at GSI (2011). Design & efficiency.

BELEN-30: 20 3He (20 atm) & 10 3He (10 atm)

Inner ring (10 counters): 29 cm

Outer ring (20 counters): 37 cm

Efficiency (1keV-1MeV) ~40%

Average up to 5MeV ~ 35%

Central hole radius: 11.5 cm (SIMBA)


252Cf neutron source detection efficiency (M.Marta):

� MCNPX simulation: (34.5±0.2)%

� Triggerless DACQ (IFIC) in MBS : (35.4±0.8)%

� Analog branch: (25.5±0.9)% (electronics)

Silicon Implantation Beta Absorber (SIMBA)

10

Results and ongoing analysis S410 experiment


Bi

Po

At

Rn

11R.Caballero-Folch, C.Domingo-Pardo et al.

Hg

Au

Pt

Tl

Pb

Bi

211Hg

215Tl

Results and ongoing analysis S410 experiment



Results and ongoing analysis:


Count

sPerformance test time correlation between neutron and β-decay for 213Tl

Counts

Time β-neutron (ms)

Time β-neutron (ms)

β

β

ε N

NP

n

n

n

1=


Detection system


Contents

Previous versions New designsDetection system New designs



14

Recent improvements for BELEN design

� The number of 3He counters has been duplicated and their pressure changed

from 20 atm to 8 atm. The cost of this improvement is around 150.000€.

� New MC simulations for future BELEN versions to perform more experiments

at JYFL (IGISOL trap) and the design with AIDA (changes on central hole

radius).


radius).

� Planarity (flat efficiency) optimization to different energy ranges up to 2MeV

or 5MeV.

� GEANT4 simulations are being done to compare MC simulations and the

correlation has been checked.

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BELEN versions designed

Name3He

countersPressure

(atm)Experiment

Ratio@

2 MeV

Ratio @

5 MeV

Average efficiency

Central hole radius

(cm)

BELEN-20 20 20 JYFL-2009 1.17 [1.60] 27% 5.5

BELEN-20 20 20 JYFL-2010 1.17 [1.60] 35% 5.5

BELEN-30 20+10 20 & 10 GSI-2011 1.17 [1.70] 35 % 11.5

(SIMBA)

BELEN-48 40+8 8 & 10 JYFL-2013 1.02 1.16 54%-39% 5.5

BELEN-48 40+8 8 & 10 DESPEC 1.04 1.15 45%-34% 8 (AIDA)


BELEN-48 40+8 8 & 10 DESPEC 1.04 1.15 45%-34% 8 (AIDA)

Observe: Central hole, num. counters & planarity

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)efficiencyn min(neutro

)efficiencyn max(neutro=Ratio

max(neutron efficiency)

min(neutron efficiency)

To define the efficiency flatness for a

range of neutron energies

5MeV

2-5MeV

BELEN design for JYFL 2013

Radius of central hole: 5.5cm.

Neutron energy range 100 keV – 5 MeV

Planarity optimization

Name 3He counters Pressure (atm) Ratio 2MeV Ratio 5MeVAverage

EfficiencyCentral hole radius (cm)

BELEN-48 40+8 8 & 10 1.02 1.16 39% 5.5


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12

3

2

1

3

total


Name 3He counters Pressure (atm) Ratio 2MeVAverage


BELEN-48 40+8 8 & 10 1.10 54% 5.5


Neutron energy range 100 keV – 2 MeV

Efficiency optimization


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3

21

1

2

3

total




Efficiency Vs planarity optimization

1MeV

1MeV

19

1MeV

5MeV

New BELEN design in progress for AIDA

Name 3He counters Pressure (atm) Ratio 2MeV Ratio 5MeVAverage


BELEN-48 40+8 8 & 10 104 115 34% 8 (AIDA)

Optimized for neutron energy range 100 keV – 5 MeV

Radius of central hole: 8 cm

Planarity optimization


20

1

3

2

3

2

1

total

New BELEN design in progress for AIDA

Name 3He counters Pressure (atm) Ratio 2MeVAverage


BELEN-48 40+8 8 & 10 106 45% 8 (AIDA)

Optimized for neutron energy range: 100 keV – 2 MeV

Radius of central hole: 8 cm

Efficiency optimization


21

total

1

2

3

1 2

3

Summary of design parameters

� Define the energy range of the neutrons to optimize the desired flat

efficiency

� Number of counters available � Polyethylene matrix


� Radius of central hole � Implantation detector and beamsize

� Knowledge of the estimation neutron background to decide the shielding

� Support structure.

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BRIKEN (BELEN @ RIKEN) meeting


� IFIC – UPC – CIEMAT – MSU – Edinburgh – GSI – RIKEN – Tennessee

� Analysis of the facility to perform experiments with BELEN + AIDA at RIKEN

� Discussion of what kind of experiments can be done and regions to explore.

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� Possibility of a campaign of measurements in the near future

� Conclusions:

� Interest of all parts involved

� Possibility to increase BELEN efficiency with RIKEN 3He counters

Conclusions (I)

� MC simulations indicates that the overall neutron detection efficiency

depends on the 3He pressure and the number of counters (among other

variables).

� The number of counters is more significant than gas pressure.

(Reason of change of the 21 counters at 20atm to 42 at 8atm)

The inner ring gives the maximum efficiency but for lower energies.


� The inner ring gives the maximum efficiency but for lower energies.

� The position of the outer ring is determinant to evaluate:

A) the efficiency of the higher energy to optimize

B) the neutron background and the shielding design due to the

thickness of the polyethylene around the crown.

� New experiments will be done with 42 counters at 8 atm (UPC) + 10

counters at 10 atm available (GSI). 24

Conclusions (II)

� BELEN is a 4π neutron detector designed to study β delayed neutron emission

� Laboratory tests and several successful experiments performed (Barcelona, JYFL,

LSC - Canfranc and GSI).

� The efficiency of the previous configurations has been validated experimentally

with 252Cf sources and some reference isotopes.


� Flat efficiency is obtained up to neutron energies of 5 MeV

�Average efficiency of 34% for 8 cm central hole (AIDA) for neutron up to 5 MeV

�Average efficiency of 45% for 8 cm central hole (AIDA) for neutron up to 2 MeV

� Neutron efficiency calibration at PTB next June 2013

� Proposal approved at JYFL for this year.

� TDR: Ongoing, expected to include calibrations at PTB improvements presented

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BELEN detector team

UPC (Barcelona) R.Caballero-Folch, F.Calviño, G.Cortès, A.Poch, C.Pretel, A.Riego, A.Torner

Old members: M.B.Gómez-Hornillos, V.Gorlychev

IFIC (València)J.Agramunt, A.Algora, C.Domingo-Pardo, D.Jordan, J.L.Taín

Work supported by the Spanish Ministry of

Economy and Competitivity under contract

FPA 2011-28770-C03-03

GSI (Darmstadt – Germany)I.Dillmann, A.Evdokimov, M.Marta

CIEMAT (Madrid)D.Cano-Ott, T.Martínez, E.Mendoza, A.García-Ríos

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