Three years of cross-section measurements of (n,xn ...

Three years of cross-section measurements of (n,xn)

threshold reactions at TSL Uppsala and NPI Řež

O. Svoboda , A. Krása, A. Kugler, M. Majerle, J. Vrzalová, V. Wagner

Supported partly from the EFNUDAT

EFNUDAT Workshop 26.5.2010

Nuclear Physics Institute, Academy of Sciences of t he Czech Republic

Department of Nuclear Reactors, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague

2

OutlineOutlineOutlineOutline

Motivation

σσσσ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

� Motivation for cross-section measurements

� Requirements for cross-section measurements

� TSL Uppsala facility

� NPI Řež facility

� Evaluation and neutron background subtraction

� Results - Comparison with EXFOR and TALYS

� Conclusion

3

Motivation for Motivation for Motivation for Motivation for σ σ σ σ measurements measurements measurements measurements ––––Energy plus Transmutation projectEnergy plus Transmutation projectEnergy plus Transmutation projectEnergy plus Transmutation project

JINR Dubna, Russia

Motivation

• E+T

• (n,xn) reactions

• E+T results

• (n,xn) in EXFOR


TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

4

(n,xn) threshold reactions(n,xn) threshold reactions(n,xn) threshold reactions(n,xn) threshold reactions

Al Au Bi Co In Ta

ReactionE thresh[MeV]

Half-life

197Au (n,2n) 196Au 8.1 6.183 d197Au (n,3n) 195Au 14.8 186.1 d197Au (n,4n) 194Au 23.2 38.02 h197Au (n,5n) 193Au 30.2 17.65 h197Au (n,6n) 192Au 38.9 4.94 h197Au (n,7n) 191Au 45.7 3.18 h

Motivation

• E+T


• E+T results

• (n,xn) in EXFOR


TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

5

E+T results E+T results E+T results E+T results –––– (n,xn) cross(n,xn) cross(n,xn) cross(n,xn) cross----section section section section faultfaultfaultfault????????

1E-7

1E-6

1E-5

1E-4

1E-3

1E-2

2 4 6 8 10 12Radial distance from the target axis [cm]

Yie

ld [1

/g*d

eute

ron]

198Au 196Au 194Au 192Au 24Na

10-7

10-6

10-5

10-4

10-3

10-2

(n,xn)cross-sections

need to be verified…

Experiment MCNPX simulation

0.0

0.5

1.0

1.5

2.0

2.5

0 5 10 15Radial distance from the target axis [cm]

exp.

yie

ld /

sim

. yie

ld

2.0 GeV 1.5 GeV1.0 GeV 0.7 GeV

Motivation

• E+T


• E+T results

• (n,xn) in EXFOR


TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

6

Current status of (n,xn) reaction knowledgeCurrent status of (n,xn) reaction knowledgeCurrent status of (n,xn) reaction knowledgeCurrent status of (n,xn) reaction knowledge

0.01

0.1

1

10

0 50 100 150

Cro

ss-s

ectio

n [b

]

Neutron energy [MeV]

209Bi(n,xn)

(n,6n)204Bi (n,7n)203Bi(n,8n)202Bi (n,9n)201Bi(n,10n)200Bi (n,11n)199Bi(n,12n)198Bi

209Bi(n,xn)

0.0

0.5

1.0

1.5

2.0

0 50 100 150Neutron energy [MeV]

Cro

ss-s

ectio

n [b

]

(n,4n)206Bi(n,5n)205Bi

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

]EXFOR

ENDF

197Au(n,4n) 194Au

0.0

0.5

1.0

1.5

2.0


Cro

ss-s

ectio

n [b

]

EXFOR

ENDF

Motivation

• E+T


• E+T results

• (n,xn) in EXFOR


TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

7

Requirements for Requirements for Requirements for Requirements for σσσσ measurementsmeasurementsmeasurementsmeasurements

Requirements for using activation method of measurement:

� high energy neutron source with good intensity

� (quasi)monoenergetic neutrons with well known spectrum

� pure samples

� good spectroscopic equipment: shielded HPGe detectors

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

Studied (mono)isotopic materials:

In all irradiations: Al, Au, Bi, I, In, Ta

In some irradiations: Co, Cu, Fe, Mg, Ni, Y, Zn

Motivation

σσσσ measurement• requirements

• exp. history

TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

8

CrossCrossCrossCross----section experiments historysection experiments historysection experiments historysection experiments history

2007 – Proposal to EFNUDAT on (n,xn) measurements – accepted

5/2008 – pilot/testing measurements at NPI Řež – 25MeV

6/2008 – measurement at TSL Uppsala – 25, 50, and 97 MeV

8/2008 – measurements at NPI Řež – 20 MeV

4/2009 – measurements at NPI Řež – 32.5 MeV

5/2009 – measurement at NPI Řež – 37 MeV

2009 – proposal to last call of EFNUDAT on further experiments at Uppsala – accepted

2/2010 - measurement at TSL Uppsala – 62, 70, 80, and 93 MeV

Autumn/2010 – planned new measurements in Řež

Motivation

σσσσ measurement• requirements

• exp. history

TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

9

TSL TSL TSL TSL Uppsala Uppsala Uppsala Uppsala ---- Blue hallBlue hallBlue hallBlue hall

Blue hall:quasi-monoenergetic neutron source based on reaction 7Li(p,n)7Be

Motivation

σ measurement

TSL Uppsala

• Blue hall

• irradiations

NPI Řež

Evaluation

Results

Conclusion

0

0.1

0.2

0.3

0.4

0.5

0.6


Neu

tron

flux

[1/M

eV (

peak

are

a=1)

]

24.7 MeV p-beam, 2 mm Li-target



Neutron spectra known for proton energies 25, 50 and 97 MeV

10

TSL Uppsala TSL Uppsala TSL Uppsala TSL Uppsala ---- irradiationsirradiationsirradiationsirradiationsProton beam energy [MeV] 25 50 977Li-target thickness [mm] 2 4 8.5

Proton beam current [ µµµµA] 5 5 2

Average energy of peak neutrons [MeV] 22 47 94

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

Peak neutron flux density [10 5 cm -2 s-1] 6 13 14.5

Motivation

σ measurement

TSL Uppsala

• Blue hall

• irradiations

NPI Řež

Evaluation

Results

Conclusion

11

Cyclotron in NPI Cyclotron in NPI Cyclotron in NPI Cyclotron in NPI ŘŘŘŘeeeežžžž• Protons 18 – 37 MeV on 7Li target

• High neutron intensities: 108 cm-2 s-1

• Well equipped spectroscopic laboratory (NSD-NPI)

BeamBeam --lineline

LiLi --targettarget

GraphiteGraphitestopperstopper

SamplesSamples

Motivation

σ measurement

TSL Uppsala

NPI Řež

• cyclotron

• neutron spectra

Evaluation

Results

Conclusion

12

Neutron spectra from p/Li source in NPINeutron spectra from p/Li source in NPINeutron spectra from p/Li source in NPINeutron spectra from p/Li source in NPI ŘŘŘŘeeeežžžž

Neutron spectra known for 20, 25, 30, and 35 MeV – Y. Uwamino et al., NIM A389 (1997) 463 – similar construction of p/Li source

Uncertainty in spectrum determination – 10%

0 10 20 30 40Neutron energy [MeV]

Num

ber

of n

eutr

ons

(1/s

r M

eV C

) E=20 MeV

E=25 MeV

E=32.5 MeV

E=37 MeV

1·1015

1.2·1015

8·1014

6·1014

4·1014

2·1014

0

Motivation

σ measurement

TSL Uppsala

NPI Řež

• cyclotron

• neutron spectra

Evaluation

Results

Conclusion

13

Evaluation processEvaluation processEvaluation processEvaluation process

Irradiation

NYield

HPGeSpectra evaluation

Cross-section

Corrections

0,94

0,95

0,96

0,97

0,98

0,99

1,00

1,01

0 2 4 6 8 10 12 14 16

Ep Et

2x2 cm emmiter

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

• process

• background 1

• background 2

• uncertainties

Results

Conclusion

14

Background subtraction 1Background subtraction 1Background subtraction 1Background subtraction 1TALYS 1.0 (TALYS 1.2)

� deterministic code

� provides complete and accurate calculation of the nuclear reactions in the energy range from 1 keV to 200 MeV

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

• process

• background 1

• background 2

• uncertainties

Results

Conclusion 0.0

0.5

1.0

1.5

2.0

2.5


Cro

ss-s

ectio

n [b

arn]

EXFOR

Talys1.2

Talys 1.0

197Au(n,2n) 196Au

15

Background subtraction 2Background subtraction 2Background subtraction 2Background subtraction 2• σ comparisons between EXFOR and TALYS 1.0 – mostly good agreement

• we believe the simulated σ shape is OK, only the absolute value can be shifted

• following the neutron spectrum knowledge, we calculated ratio between production in neutron peak and total production

• with this ratio we multiplied the yields to subtract backgroundproduction

0

1

0 5 10 15 20 25 30Energy [MeV]

Cro

ss-s

ectio

n ve

rsus

neu

tron

sp

ectr

um [-

]

32.5 MeV beamAu-196 (0.19)Bi-207 (0.65)In-111 (0.89)Bi-206 (0.99)I-124 (1.0)

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

• process

• background 1

• background 2

• uncertainties

Results

Conclusion

16

Uncertainty analysis Uncertainty analysis Uncertainty analysis Uncertainty analysis � HPGe detector calibration uncertainty: less than 3%

� Gauss-fit of the gamma peaks: > 1% (usually less than 10%)

� spectroscopic corrections uncertainty: less than 1%

� neutron spectra determination: 10%

� neutron beam intensity determination: 5% at NPI, 10% at TSL

� TALYS 1.0 versus TALYS 1.2 – differences in results around 10%

� TALYS modifications - nuclear density variations: less than 10% difference in results

� background subtraction procedure – assessed to ~10% uncertainty, but will be further studied

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

• process

• background 1

• background 2

• uncertainties

Results

Conclusion

17

197197197197Au(n,2n)Au(n,2n)Au(n,2n)Au(n,2n)196196196196Au resultsAu resultsAu resultsAu results

197Au(n,2n) 196Au

0

0.5

1

1.5

2

2.5

3

0 10 20 30 40 50 60 70 80 90 100Neutron energy [MeV]

Cro

ss-s

ectio

n [b

arn]

EXFOR

TALYS

NPI experiments

TSL experiments

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 196Au

• 194Au

• 193Au

• 192Au

Conclusion

18


Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 196Au

• 194Au

• 193Au

• 192Au

Conclusion

197Au(n,4n) 194Au

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6


Cro

ss-s

ectio

n [b

arn]

EXFORTALYSNPI experimentsTSL experiments

19


0.0

0.2

0.4

0.6

0.8

1.0

1.2


Cro

ss-s

ectio

n [b

arn]

TALYSTSL experimentNPI experiment

197Au(n,5n) 193Au

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 196Au

• 194Au

• 193Au

• 192Au

Conclusion

20


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


Cro

ss-s

ectio

n [b

arn]

TALYSTSL experiment

197Au(n,6n) 192Au

Au measured up to 188Au…

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 196Au

• 194Au

• 193Au

• 192Au

Conclusion

21

209209209209Bi(n,3n)Bi(n,3n)Bi(n,3n)Bi(n,3n)207207207207Bi resultsBi resultsBi resultsBi results

209Bi(n,3n) 207Bi

0

0.3

0.6

0.9

1.2

1.5

1.8


Cro

ss-s

ectio

n [b

arn]

EXFOR

TALYS

NPI experiments

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 207Bi

• 206Bi

•Other Bi

Conclusion

22

209209209209Bi(n,4n)Bi(n,4n)Bi(n,4n)Bi(n,4n)206206206206Bi resultsBi resultsBi resultsBi results

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 207Bi

• 206Bi

•Other Bi

Conclusion

209Bi(n,4n) 206Bi

0

0.3

0.6

0.9

1.2

1.5

1.8


Cro

ss-s

ectio

n [b

arn]

EXFOR

TALYS

NPI experiments

TSL experiments

23

Other Other Other Other 209209209209Bi(n,xn) resultsBi(n,xn) resultsBi(n,xn) resultsBi(n,xn) results

Bi measured up to 200Bi…

209Bi(n,6n) 204Bi

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


0.0

0.1

0.2

0.3

0.4

0.5

0.6


Cro

ss-s

ectio

n [b

arn] 209Bi(n,7n) 203Bi

209Bi(n,5n) 205Bi

0

0.2

0.4

0.6

0.8

1

1.2

1.4


Cro

ss-s

ectio

n [b

arn]

EXFOR

TALYS

NPI experiments

TSL experiments

0.0

0.1

0.2

0.3

0.4

0.5


209Bi(n,8n) 202Bi

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 207Bi

• 206Bi

•Other Bi

Conclusion

24

181181181181Ta(n,2n)Ta(n,2n)Ta(n,2n)Ta(n,2n)180180180180Ta resultsTa resultsTa resultsTa results

181Ta(n,2n)180Ta

0

0.5

1

1.5

2

2.5


Cro

ss-s

ectio

n [b

arn]

TALYS

EXFOR

NPI experiments

TSL experiments

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 181Ta

• 114mIn

• 24Na

• 27Mg

Conclusion

25

natnatnatnatIn(n,xn)In(n,xn)In(n,xn)In(n,xn)114m114m114m114mIn resultsIn resultsIn resultsIn results

0.0

0.4

0.8

1.2

1.6

2.0


Cro

ss-s

ectio

n [b

arn]

TALYSEXFORNPI experimentsTSL experiments

natIn(n,xn) 114mIn

In measured up to 108In…

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 181Ta

• 114mIn

• 24Na

• 27Mg

Conclusion

26

27272727Al(n,Al(n,Al(n,Al(n,αααα))))24242424Na resultsNa resultsNa resultsNa results

0

0.03

0.06

0.09

0.12

0.15


Cro

ss-s

ectio

n [b

arn]

EXFOR

TSL experiments

NPI experiments

TALYS

27Al(n, αααα)24Na

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 181Ta

• 114mIn

• 24Na

• 27Mg

Conclusion

27

27272727Al(n,p)Al(n,p)Al(n,p)Al(n,p)27272727Mg resultsMg resultsMg resultsMg results

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14


Cro

ss-s

ectio

n [b

arn]

TALYS

EXFOR

NPI experiments

TSL experiments

27Al(n,p) 27Mg

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

• 181Ta

• 114mIn

• 24Na

• 27Mg

Conclusion

28

ConclusionsConclusionsConclusionsConclusions

� Uppsala and Řež cross-section measurements covered wide range of energies (17 – 94 MeV)

� threshold reactions in Au, Bi, I, In, and Ta studied up to (n,10n)

� our results for well known cross-sections agree with other experimental data in EXFOR

� near future: finish the evaluation of cross-section measurements from Uppsala - February 2010

� autumn 2010 – planed next cross-sections measurements at NPI Řež

� further study of the background subtraction procedure and its uncertainty

Motivation

σ measurement

TSL Uppsala

NPI Řež

Evaluation

Results

Conclusion

29

AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements

We would like to thank to Dr. Bém and his colleagues for the possibility to joint their irradiations on cyclotron in Řež!

This work was supported from the EFNUDAT,grant CTU0808214 and by the F4E program of the Nuclear

Reaction Department (NPI), F4E-2008-GRT-014.

Thank you for your attention..

Three years of cross-section measurements of (n,xn ...

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