Neutrons For Science (NFS) at SPIRAL-2

Contact: [email protected], April 4, 2007

Neutrons For Science (NFS) at SPIRAL-2Neutrons For Science (NFS) at SPIRAL-2

● The spiral 2 project

● Neutron production modes

● Design

● Beam characteristics

● Irradiation facility

● Physics case

X. Ledoux and the NFS collaboration


SPIRAL-2

40MeV; 5mA

deuterons neutrons

graphite

UCx


M. Jacquemet, GANIL Colloquium, Giens, june 2006

Spiral-2 Layout


Beams delivered by the LINAG

LINear Accelerator of Ganil

Power at full intensity I=5mA, E=40 MeV P=200 kW

Challenge: radioprotection 1015 n.s

Converter composition

● Two sources

one for deuterons

one for heavy ions

● Two RFQs q/A=3

q/A=6 for heavy ions (by now optional)

● LINAG

F0 = 88 MHz T=11 ns

26 cavities

Burst width = 200 ps

● Main specifications :

5 mA of 40 MeV deuterons

1 mA for heavy ions at Emax=14,5 A.MeV

All details available on www.ganil.fr


Neutron For Science

A working group was created to study :

The possible use of the LINAG beam to built a neutron facility

The Physics case realizable at NFS

The facility will be composed of two parts :

Neutron beam

Irradiation station

Means :

Deuteron and proton beams

Thin and thick converter

Dedicated room(s)

A letter of intents was presented to the Scientific Advisory Committee of SPIRAL 2


Neutron spectra provided at NFS (1)

Deuteron break-up on Thick converter

E deut = 40 MeV

The deuteron are stopped in the converter (1cm)

Continuous beam <E> = 14 MeV

Be instead C converter allows to increase the flux by a factor of 2

Meulders et al., Phys. Med. Biol. (1975)vol 20 n°2, p235

⇒ Similar to IFMIF spectrum


Neutron spectra provided at NFS (2)

Neutron production by 7Li(p,n)7Be reaction

Thin converter (1-3 mm)

Quasi-monokinetic beam

Ep = 3 – 33 MeV

En ≈ Ep –1,6 MeV

Schumacher et al.,NIMA421 (1999) p2843

7Li(p,n)7Be


Neutron For Science Facility

Sample

Detector(s)

Converter cave

- Beam line extension

- Clearing magnet

- Beam dump

- Irradiation stations (n, p, d)

Experimental Hall- Beam(s) at 0° and 30° optional

- Collimator design ↔ beam quality

- Size (L l)ⅹ ≃ (30m ⅹ 6m)

time-of-flight measurement

measurement at desired distance

large experimental set-up


Beam repetition rate

Requirement: differentiation of 2 neutrons with the ToF t and t+T

L(m) Eth (MeV) T(s) N Imax(A)

5 0.1 1 100 50

30 0.1 6 600 8

T 1 ≃ s

T 6 ≃ s

T 1 ≃ s

T 6 ≃ s

TLINAG = 11 ns

Take only one burst over N (f = F0/N)

- burst selector

- I = Imax / N, with Imax=5mA


Energy resolution

L=30m and fast detector ⇒ high resolution measurement

HPGe detector ⇒ E/E < 5% for L=30 m

The neutron energy is measured by time-of-flight technique

Good resolution measurements require :

- A unique burst selector

- Burst duration on converter < 1ns (buncher might be needed)

t : Full time resolution :

td ≃ 1 ns scintillator

≃ 8 ns HPGe

tb ≃ 1 ns

E

E

t

t

L

L

12 2

22bd ttt


N-tof : CERN,

Spallation,L=185 m,F=0.4Hz

GELINA : Geel,

Photofission, F=800Hz,30 m

Spiral-2 : high intensity high resolution

Comparison with other neutron beam facilities

Complementary to the existing facilities

• En: from 1 MeV to 40 MeV

• High flux ⇒ small samples

coincident experiments

• Reduced flash


Comparison with other neutron beam facilities

● Disadvantages of NFS

- high frequency

- flux by burst smaller than n-tof or Gelina

- only fast neutrons (1-40 MeV)

●Advantages of NFS :

high average flux in the 1-40 MeV range :

- small samples

- coincident experiments

production mode :

- no high energy neutron (in comparison with spallation)

- reduced gamma flash (in comparison with photoreaction)

Hall size :

- desired distance between 5 and 30 m high flux or high resolution

- use of large set-up


Measurement by activation technique

- Neutron induced reaction

The sample is put very close of the converter

White source <E> = 14 MeV

>5.1011n/s/cm2 for Id=50 A

Quasi-monoenergetic (Li converter on carbon back-up)

- Proton and Deuteron induced reaction

Two irradiation stations can be installed in the converter cave :

- Off-line activity measurement in a separate room

- Detectors for flux monitoring

→ Cross-section measurement :

Imax limited to 50 A- Low power deposition on converter < 2 kW

- Reduced activation « easy » sample manipulation


Monoenergetic neutrons beam

• d + d → n + 3He Q = 3.27 MeV

- En(0 deg) = 3.2 –7.2 MeV for Ed= 0 - 4 MeV

- Gaseous or solid (TiD) targets

• d + T → n + 4He Q = 17.59 MeV

- En(0 deg) = 14 –20 MeV for Ed= 0 - 3.7 MeV

- only solid target (TiT)

Mono-energetic neutrons can be produced by the following reactions

Low energy deuteron beam (Ed < 4 MeV)

The neutron flux depend on the power the target can sustain


Converter caveroof 1,5 mwalls 2 m

TOF room :wall thickness ≈ 50cmneutron beam dump at 0 degree

Light concrete: less activation than in concrete loaded with iron

Radioprotection simulations


Radioprotection

Neutron dose calculation for 100 A d + Be (1 cm)Code PHITS (V. Blideanu)

Public area : D < 0,5 Sv/h



Possible implementation


General Physics Case

Reactions induced by fast neutrons are of first importance in the following topics :

- Fission reactors of new generation

- Fusion technology

- Studies related to hybrid reactors (ADS)

- Validation of codes

- Nuclear medicine

- Development and characterization of new detectors

- Irradiation of chips and electronics structures used in space

Workshop and reports:

International Workshop on Neutrons for Science (NFS) at SPIRAL-2, GANIL, Caen, France; 13-14 December 2004. D. Ridikas et al, “Neutrons for Science (NfS) at SPIRAL-2”, Internal report DAPNIA report 05-30, Saclay, France (2005),

A. Plompen, “Nuclear Data Needs for Nuclear Energy (fission) and Possible Contributions of SPIRAL2”, 15th Colloque GANIL, Giens, France (2006)

U. Fischer, “Nuclear data needs for fusion technology and possible contribution by SPIRAL2”, 15th Colloque GANIL, Giens, France (2006).


Neutron induced fission

• Need of data for fast neutron essentially for minor actinides

ADS, GEN IV reactors

Cross-section measurements

Neutron, gamma multiplicity and spectra

Fragment yields

• NFS short flight path → High flux

Small samples ( emitters)

Coincidence measurements

• Complementary to surrogate reactions

Limited to 10 MeV

Model dependence

• Study of the fission process

Continuous spectrum → continuous excitation energy

Coincidence experiment

(A,Z) fragment distribution


(n,X) cross section measurements

• (n,xn) reactions

Maximum in the NFS energy range

Neutron multiplication

• (n,LCP)

Gazes and default production

Energy deposition in therapy

Composite particle prediction → no model works

• In-beam -ray spectroscopy

White source and quasi-monokinetic spectrum

(n,2n), (n,np), (n,) reactions

Use of large Ge array for - coincidence measurements

• Double differential measurements (n,xn), (n,LCP)

Few data exist between 20 and 50 MeV

Use of existing detection set-ups

56Fe(n,) cross sections in several data bases.

Incident energy (MeV)

(ba

rns)


Cross-section measurement needed for fusion technology

0 10 20 30 40 5010-2

10-1

100

101

102

103

EAF-2005

p-D2O spectrum

d-Li spectrum

IEAF-2001

186W(n,n+)182mHf

, m

b

Neutron Energy, MeV

0 5 10 15 20 25 30 35 40 4510-3

10-2

10-1

100

Ditroi'00_Sig EAF20051_Nb93d2nMo92m

93Nb(d,2n)93mMo

Cro

ss S

ecti

on,

b

Deuteron Energy, MeV

EAF-2005.1

Ditroy'00

IFMIF and ITER need neutron and deuteron induced

reactions cross-section.

- Data scarce or not existing

- Large discrepancies between data bases

Material to be studied for IFMIF :

Al, Fe, Cr, Cu, Nb for cavities and beam transport elements

Be, C, O, N, Na, K, S, Ca, Fe, Cr, Ni for Li loop

• Cross-section measurement by activation technique

• 2 irradiation stations :

- Neutron induced reactions

- Proton and deuteron

• Imax limited to 50 A

- Power deposition on converter < 2 kW

- Reduced activation « easy » sample manipulation


Summary

- White and quasi-monokinetic spectra in the 1-40 MeV range

- Neutron beams with high flux and good energy resolution

- Complementary to the existing n-tof facilities

- Irradiation stations for activation measurements (n, p, d)

- Intensity on the converter limited to 50 A

• reduced activation

• light converter design

- NFS is somewhat independent of RIB production

- Could start as soon as the LINAG is ready (2011)

The LINAG characteristics are particularly well adapted to a neutron facility at SPIRAL-2


The NFS collaborationThe NFS collaboration

X. Ledoux1), M. Aïche2), G. Ban3), G. Barreau2), P. Baumann4), P. Bem5), V. Blideanu6), J. Blomgren7) , S.

Czajkowski2), P. Dessagne4), E. Dupont6), T. Ethvignot1), U. Fischer8), F. Gunsing6), B. Jacquot9), B.

Jurado2), M. Kerveno4), F. R. Lecolley3), J. L. Lecouey4), F. Negoita10), S. Oberstedt11), M. Petrascu10),

A.J.M. Plompen11), F. Rejmund9), D. Ridikas6), G. Rudolf4), O. Shcherbakov12), S.P. Simakov8), J. Taïeb1)

1) Service de Physique Nucléaire, CEA/DIF, BP 12, 91980 Bruyères-le-Châtel Cedex, France

2) Centre d’Etudes Nucléaires de Bordeaux-Gradignan, 33175 Gradignan, France

3) Laboratoire de Physique Corpusculaire, ISMRa et Université de Caen, CNRS/IN2P3,France

4) Institut Pluridisciplinaire Henri Curien, Strasbourg, France

5) Nuclear Physics Institute, 25068 Řež, Czech Republic

6) Centre d’Etudes Nucléaires de Saclay, DSM/DAPNIA, France

7) Department of Neutron Research, Uppsala University, Uppsala, Sweden

8) Forschungszentrum Karlsruhe, Institute for Reactor Safety, Karlsruhe, Germany

9) GANIL, CEA/CNRS, Caen, France

10) NIPNE, Bucharest, Romania

11) Institute for Reference Materials and Measurements, Geel, Belgium

12) PNPI, Gatchina, Russia

Documents

Neutrons For Science (NFS) at SPIRAL-2