Ondřej Svoboda

• Nuclear Physics Institute, Academy of Sciences of Czech Republic• Department of Nuclear Reactors, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague

Cross-section measurements of the (n,xn) threshold reactions

OutlineOutline

• Motivation for Motivation for measurements measurements• Requirements Requirements ffoorr measurements measurements• TSL Uppsala experimentTSL Uppsala experiment• Experiments on Cyclotron in ŘežExperiments on Cyclotron in Řež• Cross-section conclusionCross-section conclusion

- Motivation for measurements

- Requirements

- TSL Uppsala

- Cyclotron Řež

- Conclusion

Motivation for Motivation for measurement – E+T measurement – E+T

)()(

)(

11

1

)(

0

irrreal tirr

t

t

foillive

real

areaP

irrabspyield e

t

e

e

mt

t

CCoiEI

CCSN

- Motivation for measurements • Energy plus Transmutation

• Yield to neutron flux

- Requirements

- TSL Uppsala

- Cyclotron Řež

- Conclusion

We want to measureWe want to measure

Yield to neutron flux problemYield to neutron flux problem

Solving a Fredholm equation we can find Φ(E):Solving a Fredholm equation we can find Φ(E):

dEEENbeam

thresh

E

E

yield )()(

We would like to find! We would like to find! (Up to now only MCNPX simulation)(Up to now only MCNPX simulation)

Poor knowledge of Poor knowledge of

MeasuredMeasured in E+T in E+T

197Au(n,2n)196Au

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 10 20 30 40 50Neutron energy [MeV]

Cro

ss-s

ectio

n [b

arn]

EXFORENDF

197Au(n,4n)194Au

0.0

0.5

1.0

1.5

2.0

0 10 20 30 40 50Neutron energy [MeV]

EXFORENDF

- Motivation for measurements • Energy plus Transmutation

• Yield to neutron flux

- Requirements

- TSL Uppsala

- Cyclotron Řež

- Conclusion

Requirements for Requirements for -measurements by activation method: -measurements by activation method:

- high energy neutron source with good intensityhigh energy neutron source with good intensity

- (quasi)monoenergetic neutrons with well known spectrum (quasi)monoenergetic neutrons with well known spectrum

- pure monoisotopic samples pure monoisotopic samples

- good spectroscopic equipment – good spectroscopic equipment – and X-rays spectrometersand X-rays spectrometers

- knowledge about the corrections on beam fluctuation, knowledge about the corrections on beam fluctuation, self- absorption, non-point like emitters… self- absorption, non-point like emitters…

Requirements Requirements ffoorr measurements measurements

An

yield

NN

ASN

Evaluation process:Evaluation process:

Irradiation HPGe Spectra evaluation Corrections NIrradiation HPGe Spectra evaluation Corrections NYieldYield

- Motivation for measurements

- Requirements • Equipment • Materials

- TSL Uppsala

- Cyclotron Řež

- Conclusion

Measured materialsMeasured materials

ReactionReactionEE threshthresh

[MeV][MeV]Half-lifeHalf-life

197197Au (n,2n) Au (n,2n) 196196AuAu 8.18.1 6.183 d6.183 d

197197Au (n,3n) Au (n,3n) 195195AuAu 14.814.8   186.1 d186.1 d

197197Au (n,4n) Au (n,4n) 194194AuAu 23.223.2 38.02 h38.02 h

197197Au (n,5n) Au (n,5n) 193193AuAu 30.230.2 17.65 h17.65 h

197197Au (n,6n) Au (n,6n) 192192AuAu 38.938.9 4.94 h4.94 h

197197Au (n,7n) Au (n,7n) 191191AuAu 45.745.7 3.18 h3.18 h

In Řež also In Řež also measured:measured:

Mg, Ni, Fe, ZnMg, Ni, Fe, Zn

iodine iodine (KIO(KIO44))

- Motivation for measurements

- Requirements • Equipment • Materials

- TSL Uppsala

- Cyclotron Řež

- Conclusion

TSL UppsalaTSL Uppsala- Protons on Li target or spallation sourceProtons on Li target or spallation source

- Neutrons with energies 11-174 MeVNeutrons with energies 11-174 MeV

- Well known beam and neutron spectrumWell known beam and neutron spectrum

- Motivation for measurements

- Requirements

- TSL Uppsala • Introduction • Blue hall • Experiment • Measurements

- Cyclotron Řež

- conclusion

- E+T:1.6 GeV d+

- Simulations &

comparisons

- Data share

- E+T conclusion

1E0

1E2

1E4

1E6

1E8

1E-7 1E-5 1E-3 1E-1 1E+1 1E+3Neutron Energy [MeV]

Neu

tro

n f

lux

den

sity

[1/

(cm

2.s)

]

spallation source at JINR

quasi-monoenergetic source at TSL102

104

108

106

0 10-7 10-3 10-5

10-1 101 103

TSL Uppsala – Blue hallTSL Uppsala – Blue hall- Motivation for measurements

- Requirements

- TSL Uppsala • Introduction • Blue hall • Experiment • Measurements

- Cyclotron Řež

- Conclusion

Experimental setup Experimental setup in the Blue hallin the Blue hall

Neutron spectraNeutron spectra

TSL Uppsala - irradiationsTSL Uppsala - irradiations

- 3 irradiations on the Li target – 25- 3 irradiations on the Li target – 25,, 50 50,, and and 100100 MeV p+ MeV p+- Motivation for measurements

- Requirements

- TSL Uppsala • Introduction • Blue hall • Experiment • Measurements

- Cyclotron Řež

- Conclusion

June 2008, supported by June 2008, supported by EFNUDAT programEFNUDAT program

- one irradiation on the ANITA - one irradiation on the ANITA spallation target – 1spallation target – 1880 MeV p+0 MeV p+

Proton beam energy [MeV] 24.68 ± 0.04 49.5 ± 0.2 97.9 ± 0.3

Li-target thickness [mm] 2 4 8.5

Proton beam current [A] 10 10 5

Average energy of peak neutrons [MeV] 21.8 46.5 94.7

Fraction of neutrons in the peak [%] 50 39 41

Peak neutron flux density [105 cm-2 s-1] 1.3 2.9 4.6

TSL Uppsala TSL Uppsala – spectroscopic measurements– spectroscopic measurements

- 8 hours 8 hours each irradiationeach irradiation

- one day of spectroscopic measurementsone day of spectroscopic measurements after each irradiation after each irradiation

Au, Al, Bi, In, Ta, I samplesAu, Al, Bi, In, Ta, I samples

Present status:Present status:

Finished yields evaluationFinished yields evaluation: ratio Řež – Uppsala : ratio Řež – Uppsala ~~ 1000 1000 Now Now waiting waiting forfor the beam data… the beam data…to be to be completecompletedd soonsoon

- Motivation for measurements

- Requirements

- TSL Uppsala • Introduction • Blue hall • Experiment • Measurements

- Cyclotron Řež

- Conclusion

Cyclotron ŘežCyclotron Řež

- Protons on Li targetProtons on Li target

- Neutrons with energies 10-37 MeVNeutrons with energies 10-37 MeV

- Good intensities: 10Good intensities: 1088 n cm n cm-2 -2 ss-1-1

- Well equipped spectroscopic Well equipped spectroscopic laboratory (NSD-NPI)laboratory (NSD-NPI)

- Motivation for measurements

- Requirements

- TSL Uppsala

- Cyclotron Řež • Introduction • Experiments • Preliminary results

- Conclusion

BeamBeam-line-line

Li-targetLi-target

GraphiteGraphite stopper stopper

SamplesSamples

Cyclotron Řež – experimentsCyclotron Řež – experiments

- Up to now 2 experiments: 20 and 25 MeVUp to now 2 experiments: 20 and 25 MeV

- Au, Al, Bi, In, Ta, I, Ni, Fe, Mg, ZnAu, Al, Bi, In, Ta, I, Ni, Fe, Mg, Zn

- next irradiations will hopefully be in near futurenext irradiations will hopefully be in near future

0E+00

4E+14

8E+14

1E+15

2E+15

0 10 20 30 40Neutron energy [MeV]

20 MeV25 MeV30 MeV35 MeV40 MeV

.1014

.1014

0

n [

1/s

r M

eV

C]

.1015

.1015

- Motivation for measurements

- Requirements

- TSL Uppsala

- Cyclotron Řež • Introduction • Experiments • Preliminary results

- Conclusion

0

0.25

0.5

0.75

1

1.25

1.5

20 25 30 35 40Energy [MeV]

Cro

ss-s

ecti

on

[b

arn

]

EXFOR dataOur value - Řež

Cyclotron Řež – experimental resultsCyclotron Řež – experimental results

0.0

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1.0

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2.0

2.5

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0 10 20 30 40Energy [MeV]

Cro

ss-s

ecti

on

[b

arn

]EXFOR dataOur value - ŘežTentative data!Tentative data!

Evaluation not yet Evaluation not yet ready…ready…

An

yield

NN

ASN

Number of Number of neutrons in peakneutrons in peak

196196AuAu

194194AuAu- Motivation for measurements

- Requirements

- TSL Uppsala

- Cyclotron Řež • Introduction • Experiments • Preliminary results

- Conclusion

ConclusionConclusion

– Uppsala and Řež cross-section measurements Uppsala and Řež cross-section measurements covered wide spectrum of energies (20-100 MeV)covered wide spectrum of energies (20-100 MeV)

– Preliminary results show we are close to known Preliminary results show we are close to known cross-section valuescross-section values

– Near future – finalize experiment analysisNear future – finalize experiment analysis – – next experiments at Řež next experiments at Řež

– Farther future – next experiments at UppsalaFarther future – next experiments at Uppsala?? – – application of the results application of the results

on the E+T on the E+T experiments experiments – – publish the measured publish the measured

cross-sections cross-sections with respect to be with respect to be involved in the involved in the EXFOR EXFOR library if possiblelibrary if possible

- Motivation for measurements

- Requirements

- TSL Uppsala

- Cyclotron Řež

- Conclusion

Thank you for your attention..