Neutron production in large Pb/U assembly irradiated by 0.7 GeV protons Ondřej Svoboda

Neutron production in Neutron production in large Pb/U assembly large Pb/U assembly irradiated by 0.7 GeV irradiated by 0.7 GeV

protonsprotons

Ondřej SvobodaOndřej Svoboda

22.4. 2006 Řež

Work leader: RNDr. Vladimír Wagner CSc.

18 - 21. 4. 2006 2AER Working Group "f" session - Třešť

IntroductionIntroduction• Within my Diploma thesis I worked on one of the Within my Diploma thesis I worked on one of the

experiments from project „Energy plus experiments from project „Energy plus Transmutation“Transmutation“

• Project „Energy plus Transmutation“ dealth with Project „Energy plus Transmutation“ dealth with problematics of neutron sources, that will be problematics of neutron sources, that will be sutiable for future ADTT sutiable for future ADTT

• Until now a lot of experiments within the E+P Until now a lot of experiments within the E+P program:program:

- - target material and geometry tests – thick x thin targettarget material and geometry tests – thick x thin target

- charged particle source – different particles, energy, - charged particle source – different particles, energy, intensity intensity

- transmutation abilities – iodine, americium, radium, - transmutation abilities – iodine, americium, radium, plutonium samplesplutonium samples

- large assemblies with natural uranium blanket- large assemblies with natural uranium blanket


Main goals of the Main goals of the experimentexperiment

• Study spallation reactions and the density Study spallation reactions and the density of the neutron fluxes in large assemblies of the neutron fluxes in large assemblies from U and Pbfrom U and Pb

• Comparison between experimental results Comparison between experimental results and simulations done in MCNPX , and simulations done in MCNPX , deducating results with respect to used deducating results with respect to used models and librariesmodels and libraries

• Verification of the hi-energy neutron Verification of the hi-energy neutron cross-sections librariescross-sections libraries

• Neutron balance and multiplication factor Neutron balance and multiplication factor studystudy


Spallation reactionsSpallation reactions• For most transmutation reactions we need strong For most transmutation reactions we need strong

neutron fields (neutron fields (~~10101616 n/cm n/cm22) =) =>> searching for good searching for good sourcesource

• High energy charged particles produce a lot of High energy charged particles produce a lot of neutrons by reactions with heavy elements (spallation neutrons by reactions with heavy elements (spallation reactions)reactions)


ExperimentExperiment• Carried out in June, 2004 on Nuclotron in LHE JINR Carried out in June, 2004 on Nuclotron in LHE JINR

Dubna, Russia Dubna, Russia • Incident particles: protons of energy 0.7 GeV; total Incident particles: protons of energy 0.7 GeV; total

number of protons counted by beam integrator: number of protons counted by beam integrator: 5.19*105.19*101313 (big uncertainity) (big uncertainity)

• Target: Pb rod surrounded by natural uraniumTarget: Pb rod surrounded by natural uranium• Irradiation time: 8 hours 51 minutesIrradiation time: 8 hours 51 minutes• Beam inlet and neutron production were measured by Beam inlet and neutron production were measured by

the method of neutron activation analysisthe method of neutron activation analysis


Nuclotron acceleratorNuclotron accelerator Superconductive accelerator – up to 12,8 GeV for Superconductive accelerator – up to 12,8 GeV for

protons, or 6 GeV on nucleon (possibility of acceleration protons, or 6 GeV on nucleon (possibility of acceleration up to U)up to U)

Extraction time 10 sExtraction time 10 s Beam intensity 10Beam intensity 1088 up to 10 up to 101111

Superconducting magnets from NbTi alloy – cooled down Superconducting magnets from NbTi alloy – cooled down to 4,5 Kto 4,5 K

Perimetre 251,5 m, weight of cooled magnets over 80 Perimetre 251,5 m, weight of cooled magnets over 80 tonstons

Still is waiting for reconstruction + booster constructionStill is waiting for reconstruction + booster construction


TargetTarget• Target – thick Pb rod (lenght Target – thick Pb rod (lenght

48 cm, diameter 8,4 cm), 48 cm, diameter 8,4 cm), divided into 4 partsdivided into 4 parts

• Activation detectors – placed Activation detectors – placed between the target parts and between the target parts and also before and behind + also before and behind + around the blanketaround the blanket

• Target was surrounded by Target was surrounded by natural uranium blanket, U in natural uranium blanket, U in form of rods (totaly 206,4 kg)form of rods (totaly 206,4 kg)

• Whole setup placed in wooden Whole setup placed in wooden box, walls filled with box, walls filled with polyethylen (biological polyethylen (biological shielding)shielding)

• On inner walls – Cd plate – On inner walls – Cd plate – shielding against thermal shielding against thermal neutronsneutrons


Beam monitorsBeam monitors• In front of the target – two beam monitors => exact In front of the target – two beam monitors => exact

measurement of beam intensity, profile and positionmeasurement of beam intensity, profile and position• Big monitor – total proton fluence Big monitor – total proton fluence • Small monitors – position and profile measurementsSmall monitors – position and profile measurements• Activation materials: Al and Cu foilsActivation materials: Al and Cu foils


Selected isotops in beam Selected isotops in beam monitorsmonitors

Izotop line energy (keV) Half-life (h) Line intensity Cross-section [mbarn]

Cu foils

58Co 810,775 1700,6 99 42,7

52Mn

744,233

134,2

90 9,9

935,538 94,5 9,9

1434,068 100 9,9

48V983,517

383,4100 11,5

1312,096 97,5 11,5

47Sc 159,377 80,4 68,3 2,3

44Sc 1157,031 3,9 99,9 5,1

44mSc 271,13 58,6 86,7 4,0

Al foils

24Na1368,55

14,96100 10,4

2754,10 99,9 10,4

7Be 477,595 1274,9 10,5 5,7

22Na 1274,53 22792,6 99,9 13,8

• Beam monitors were measured on HPGe detector – 2 types of measurements (short/long)


Beam monitors - Beam monitors - ResultsResults

• Evaluation of the beam monitors had fundamental Evaluation of the beam monitors had fundamental importance for whole experiment!importance for whole experiment!

• total proton flux through big detector - 1.22(5)x1013

• total proton flux through small detector - 0.90(5)x1013

• beam shift 0.5(1) cm up and 0.1(1) cm left

12

3S1

S2

S34,0E+11

6,0E+11

8,0E+11

1,0E+12

1,2E+12

1,4E+12

1,6E+12

1,8E+12

Nu

mb

er o

f p

roto

ns

..

.

Weighted average number of protons


Detection of rising Detection of rising neutronsneutrons

• Neutrons comming from spallation reactions in Neutrons comming from spallation reactions in target were measured by the method of neutron target were measured by the method of neutron activation analysisactivation analysis

• Used activation materials - Au, Al, Bi, Y, Co foilsUsed activation materials - Au, Al, Bi, Y, Co foils• Foils properties: squares cca 2x2 cm, weight Foils properties: squares cca 2x2 cm, weight ~~ 1 g, 1 g,

thickness thickness ~~ 0,1 mm (according to foil material), 0,1 mm (according to foil material), totaly some 150 piecestotaly some 150 pieces

ReactionTreshold energy

[MeV] Half-life

197Au (n,2n) 196Au 8,1 6,183 d

197Au (n,3n) 195Au 14,8 186,1 d

197Au (n,4n) 194Au 23,2 38,02 h

197Au (n,5n) 193Au 30,2 17,65 h

197Au (n,6n) 192Au 38,9 4,94 h

197Au (n,7n) 191Au 45,7 3,18 h


Evaluation of Evaluation of the foilsthe foils

• Foils were measured on Foils were measured on HPGe detectorsHPGe detectors

• Evaluation of the measured Evaluation of the measured spectra was done in the spectra was done in the Deimos32 program – it fits Deimos32 program – it fits the gamma-peaks to Gauss the gamma-peaks to Gauss curvescurves

• Fitted peaks were assigned Fitted peaks were assigned to the responsive isotopesto the responsive isotopes

• Yields of produced isotopes Yields of produced isotopes have been computed with have been computed with respect to all corrections respect to all corrections (decay during the (decay during the irradiation, coincidences, irradiation, coincidences, unequable irradiation, unequable irradiation, square emitors..) square emitors..)


Correction on unstable Correction on unstable irradiationirradiation

- Nuclotron as an experimental accelerator of charged - Nuclotron as an experimental accelerator of charged particles for a wide range of energies doesnparticles for a wide range of energies doesn`t`t work work in our case very goodin our case very good

Isotop Ba Half-life

198Au 0,9965 64,684 h

44mSc 0,9962 58,6 h

24Na 0,9849 14,959 h

191Au 0,9304 3,18 h

Print-out from the beam integrator

0,0E+00

5,0E+09

1,0E+10

1,5E+10

2,0E+10

2,5E+10

3,0E+10

3,5E+10

0 5000 10000 15000 20000 25000 30000 35000

Time from irradiation start [s]

Inte

nsi

ty .

.


Longitudinal distributions of Longitudinal distributions of produced isotopes in Au and Al produced isotopes in Au and Al

foilsfoils

3 cm from the target axis

10 cm from the target axis

1,E-08

1,E-07

1,E-06

1,E-05

1,E-04

1,E-03

0 10 20 30 40 50

Distance from the beginning of the target [cm]

Yie

ld [1

/g*p

] ..a

198Au 196Au 194Au 192Au 24Na

1,E-07

1,E-06

1,E-05

1,E-04

1,E-03

0 10 20 30 40 50Distance from the beginning of the target [cm]

Yie

ld [1

/g*p

]

..

198Au 196Au 194Au 192Au 24Na


Radial distribution of Radial distribution of produced isotopes in Au and produced isotopes in Au and

Al foils – first gapAl foils – first gap

1,E-07

1,E-06

1,E-05

1,E-04

1,E-03

2 3 4 5 6 7 8 9 10 11

Distance from the centre [cm]

Yie

ld [

1/g

*p]

..

198Au 196Au 194Au 192Au 24Na


Comparison between Comparison between experimental data and experimental data and

simulationssimulations

0.7 GeV

0.0

0.5

1.0

1.5

0 2 4 6 8 10 12

exp/

sim

Au196 Au194

Distance from the centre [cm]Longitudial distance [cm]

• Simulations done in MCNPX 2.4.0 and 2.5.0

Radial direction Longitudial direction

0.7 GeV

0.0

0.5

1.0

1.5

-10 0 10 20 30 40 50

exp

/sim

Au196 Au194


ConclusionConclusion• Main aim of this experiment was a research of the Main aim of this experiment was a research of the

neutron distribution in the setup, simulation of the neutron distribution in the setup, simulation of the setup in MCNPX and comparing of obtained results setup in MCNPX and comparing of obtained results

• At present we are finishing with the results At present we are finishing with the results interpretation and we are preparing a summary reportinterpretation and we are preparing a summary report

• Results of the beam determination were used as a base Results of the beam determination were used as a base for the report “The beam intensity determination – the for the report “The beam intensity determination – the Nuclotron experiment June 2004” – send to all E+T Nuclotron experiment June 2004” – send to all E+T collaborationcollaboration

• So far the last E+T experiment ran through in So far the last E+T experiment ran through in November 2005 – deuterons 1.26 GeV, next experiment November 2005 – deuterons 1.26 GeV, next experiment is planned to be carried out without the polyethylene is planned to be carried out without the polyethylene shielding – June 2006shielding – June 2006

Thank you for your attention..

Neutron production in large Pb/U assembly irradiated by 0.7 GeV protons Ondřej Svoboda

Documents

Transcript of Neutron production in large Pb/U assembly irradiated by 0.7 GeV protons Ondřej Svoboda