1

Nuclear Activation Techniques to measure the energy distribution

of laser-accelerated protons bunches

T.Bonnet, M.Comet, D.Denis-petit, F. Gobet, F. Hannachi, M. Tarisien and M. VersteegenCentre d’Etudes Nucléaires de Bordeaux Gradignan

(CENBG/ Université de Bordeaux/CNRS-IN2P3)

Palaiseau, June 7th 2012

2

Nuclear Activation

x +TR+ yT (x, y) R

A(t) = nx σTR NT z λe-λt T1/2 = ln(2) / λ

A : activity (Bq)NT : nuclei density of the target (cm-3)nxnumber of incident particlesz : target thickness (cm)TR : reaction cross section (cm²)

A(t) = NR(t) λ

tT

E

E

TRx ezNdEEE

dE

dntA

max

min

)()()(

x

T

y

R

RRadioactive constanteHalf life period

3

High flux of energy

Optik & Photonik June 2010 No. 2

107

108

109

1010

1011

0 5 10 15 20

IOQ

LOA

No

mb

re d

'éle

ctro

ns

(MeV-1

.sr-1

)

Energie (MeV)

)IOQ(0N

)LOA(0N

Target Al 10 µm

TLOA≈7 MeV

TIOQ≈2,5 MeV

107

108

109

1010

1011

0 5 10 15 20

IOQ

LOA

No

mb

re d

'éle

ctro

ns

(MeV-1

.sr-1

)

Energie (MeV)

)IOQ(0N

)LOA(0N

Target Al 10 µm

TLOA≈7 MeV

TIOQ≈2,5 MeV

Electron energy (MeV)

Ele

ctro

n y

ield

(M

eV-1

sr-1)

Physical signal in a detector

E ~ 0.1 J (~1012 MeV) in few ns

P ~ 100 MW

~108 W/cm²

Target Al 10µm2.1019 W/cm² @ 100TW LULI

4

Nuclear Time Multiplexer

target

Laser

x Particles

Radioactive period is a time multiplexer

Each nucleus is a detector : no saturation

Activity measurement give information on number or radioactive nuclei number of particles passing through the target

z

Stan

dard

nuc

lear

phys

ic d

etec

tor

5

target

Laser

z

Projectile Type Discrimination

x Particles x’ Particles

Stan

dard

nuc

lear

phys

ic d

etec

tor

T (x, y) R

T (x’, y’) R’

t'T

max'E

min'E

'TR'xt

T

maxE

minE

TRx e'zNdE)E()E(

dE

dnezNdE)E()E(

dE

dn)t(A

Time (min-1)

6

How to deduce energy distribution?

Time (min)

Act

ivity

(m

in-1

) 50 µm 75 µm 100 µm 100 µm 100 µm

k foils stack

target

Laser

x Particles

*Knowing the stopping power of x particles in the matter*even Better : Simulating particles interactions with matter : GEANT4 simulations

7

How to deduce energy distribution?

Response function of the stack :GEANT4 simulations

1 incident particle E1 NR11 ; NR12 ; … ; NR1j ; …... NR1k radioisotopes in each k foils

1 incident particle E2 NR21 ; NR22 ; … ; NR2j ; …... NR2k radioisotopes in each k foils

n

i

1

E

E

E

Rk

Rj

1R

N

N

N

RnkRikk1R

RnjRijj1R

1Rn1Ri11R

NNN

NNN

NNN

n

i

1

E

E

E

Rk

Rj

1R

N

N

N

=

1 incident particle En NRn1 ; NRn2 ; … ; NRnj ; …... NRnk radioisotopes in each k foils

………………………………..

Response function matrix

A

n

i

1

E

E

E

=

E RN

RN

dN/dE(E)

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E+12

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Energy (MeV)

No

mb

er o

f p

arti

cles

(/M

eV)

E1 E2 E3 E4 Ei En........................................... .............................................................................

stackstackstack

8

How to deduce energy distribution?

Response function of the stack

kj

1j

2

RjcalRj NN exp²

calRk

calRj

cal1R

N

N

N

calRN A hypoE

Least Squares Minimization varying on k foilshypoE

Measured radioisotope in each foil

exp

exp

exp

Rk

Rj

1R

N

N

N

expRN

Energy distribution of incident particles

dN/dE(E)

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E+12

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Energy (MeV)

No

mb

er o

f p

arti

cles

(/M

eV)

E1 E2 E3 E4 Ei En........................................... .............................................................................

stackstackstack

9

Beta+ radioactivity

Scintillators Scintillators

511keV 511keV

++e- 2

511keV 511keV

511keV 511keV

++e- 2

Two 511 keV photons detected in coïncidence low noise : 20 counts / hour

stack

Target

Laser

x Particles

stackstack

Target

Laser

x Particlesx Particles

T1/2 = several minutes

10

NATALIE* detection system

NATALIE detection system : 16 pairs of NaI(Tl) 16 foils measured together.

Nuclear Activation Techniques for Analysis of Laser Induced Energetic particles

- compact electronic system

- energy, time, dead time measured

GEANT4 efficiency calculations for*different energy release by beta+ decays *extended sources

63Zn source diameter (cm)

β+

det

ectio

nef

ficie

ncy

(%)

63Zn source diameter (cm)

β+

det

ectio

nef

ficie

ncy

(%)

11

Copper field of applications

Natural copper : 2 stable isotopes 63Cu @ 69,17 %65Cu @ 30,83 %

65Cu (n,2n)64Cu 64Cu → 64Ni + e+ + νe T1/2(64Cu) = 12.70 h and Ethr = 10.1 MeV

Nuclear reactions with neutrons

Nuclear reactions with electrons : no nuclear reactions

nne- γe- γ

Nuclear reactions with protons

63Cu (p,n)63Zn 63Zn → 63Cu + e+ + νe T1/2(64Cu) = 38.5 min and Ethr = 4 MeV

Nuclear reactions with gamma rays

63Cu (,n) 62Cu 62Cu → 62Ni + e+ + νe T1/2(62Cu) = 9.73 min and Ethres = 10.8 MeV

63Cu (,2n) 61Cu 61Cu → 61Ni + e+ + νe T1/2(61Cu) = 3.33 h and Ethres = 19.74 MeV

nne- γe- γ

12

Nuclear Activation is everywhere Not only copper ; Carbon also…

Together energy and space distributions

Least Squares Minimization

Parameter Optical Densitometry

Nuclear activation

E0 (MeV) 0.86 ± 0.08 1.2 ± 0.1

Ecut (MeV) 17.1 ± 1.8 16.1 ± 0.1

n0 protons (1.65 ± 0.14).1012 (3.0 ± 0.3).1012

12C (p,)13N 13N → 13C + e+ + νe T1/2(13N) = 9.96 min and Ethr = 0 MeV

13

Nuclear Activation is everywhere

Even IP…

Irradiation de l'IP (acq: 400s)

10

100

1000

10000

100000

0 500 1000 1500 2000

Energie (keV)

511keV

19F (197keV)

19F (110keV)

1236keV

40K (1461keV)

1350 - 1359keV

1263keV

Al (844keV)Al (1013keV)

1635keV

Protons @ 3.1 MeV on TR image plate

Spectrum obtained with a Germanium detector

14

In the Future

Autoradiography on counting activation station

*Imaging Plate :- Spatial distribution of the particle bunch

*Activation :- Absolute numbers because of response stability of activation- any β+ radioisotopes ; large choice of activation sample matter

Scintillators Scintillatorsγ (511 keV)

β+ emissionγ (511 keV)

Scintillators Scintillatorsγ (511 keV)

β+ emissionγ (511 keV)

IP IP

15

In the Future

Matrix modelisation of the stack

calRk

calRj

cal1R

N

N

N

calRN A hypoE

Response function of the whole stack long GEANT4 calculation

k foils stack

Stopping power of a foil type j

Energy distribution at the entrance of each foil j :

Response function of each foil type number of radioisotopes on each foil :

121j EEE ...jE hypoE

jE

calRjN (NR1j … NR2j … NRnj) jE

16

In the Future

User friendly modular counting station

Collaboration with a company to develop compact and modular electronics

Depends on community demand

17

Conclusion

Possible spatial distribution measurement with autoradiography techniquePossible simplifications of the method User friendly tools

With activation techniques :- No flux saturation- Stable response function, no surrounding conditions dependence- Particle responses discrimination

Different materials can be activated :- Pure material (copper ; carbon ; …)- Mixed material (alloy, powders, etc…)- Detectors (RCF, IP, …)

18

Conclusion

Thank you for your attention

19

Conclusion