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Study of the fission dynamics via Isomeric Ratio Measurements at Lohengrin - Development of a new Gas Filled Magnet spectrometer within the FIPPS project A. Chebboubi, G. Kessedjian, C. Sage, O. Meplan LPSC, Universit Grenoble-Alpes,

slide-1
SLIDE 1
  • A. Chebboubi, G. Kessedjian, C. Sage, O. Meplan

LPSC, Université Grenoble-Alpes, CNRS/IN2P3, Grenoble

  • H. Faust, U. Köster, A. Blanc, P. Mutti

Institut Laue-Langevin, Grenoble

  • O. Serot, O. Litaize

CEA-Cadarache, DEN/DER/SPRC/LEPh

  • T. Materna, S. Panebianco

CEA Saclay, DSM/IRFU/SPhN

Séminaire Doctorant, LPSC, Juin 2014

1

Study of the fission dynamics via Isomeric Ratio Measurements at Lohengrin

  • Development of a new Gas Filled Magnet spectrometer within the

FIPPS project

slide-2
SLIDE 2
  • Nuclear fission and usefulness of nuclear data for

applications and fundamental physics

  • Development of a new spectrometer : Gas Filled Magnet

(GFM)

  • Properties of a GFM : experimental outcome
  • Comparison with a Monte Carlo Calculation
  • Isomeric Ratio measurements at Lohengrin (ILL)

Séminaire Doctorant, LPSC, Juin 2014

2

Outline

slide-3
SLIDE 3
  • Nuclear fission and usefulness of nuclear

data for applications and fundamental physics

  • Development of a new spectrometer : Gas Filled Magnet (GFM)
  • Properties of a GFM : experimental outcome
  • Comparison with a Monte Carlo Calculation
  • Isomeric Ratio measurements at Lohengrin (ILL)

Séminaire Doctorant, LPSC, Juin 2014

3

Outline

slide-4
SLIDE 4

Nuclear Fission Process

Discovered by Hahn, Strassman and Meitner in 1938 → Chemistry Nobel Prize 1944 A heavy nucleus is broken into two lighter fragments. Emission of a few particles (neutron, 𝛿)

s

𝟐𝟏−𝟑𝟏 𝟐𝟏−𝟐𝟕 − 𝟐𝟏−𝟐𝟑 𝟐𝟏−𝟕 − 𝟐𝟏𝟘

Séminaire Doctorant, LPSC, Juin 2014

4

Part 1 : Nuclear Fission and Context of Nuclear Data

slide-5
SLIDE 5

 Impact of fission yields on the current and innovative fuel cycles 𝑍 𝐵, 𝑎, 𝐹∗, 𝐾𝜌 = 𝑍 𝐵, 𝑎 × 𝑄(𝐹∗, 𝐾𝜌)

  • Inventory of spent fuel
  • Isotopic composition → Residual power

𝑍(𝐵, 𝑎)

  • Radiotoxicity of spent fuel
  • Modeling prompt particle emission (n/𝛿)

→ foreseen material damage/heating 𝑄 𝐹∗, 𝐾𝜌 in reactor studies

Context of the fission yield studies

5

Séminaire Doctorant, LPSC, Juin 2014 Part 1 : Nuclear Fission and Context of Nuclear Data

slide-6
SLIDE 6

𝑍 𝐵, 𝑎, 𝐹, 𝐾𝜌 = 𝑍 𝐵, 𝑎 × 𝑄(𝐹, 𝐾𝜌)  Measurements for fission process study

  • Improving the predictive power of fission models is necessary for the evaluations

at different neutron energies → 𝑍 𝐵, 𝑎, 𝐹, 𝐾𝜌

  • Lack on dynamical aspect for fission process modelisation
  • Inconsistency between Models or evaluations and Experiments for heavy

fragments and symmetric region

Context of the fission yield studies

6

Séminaire Doctorant, LPSC, Juin 2014

Disagreement between fission models and experimental data assessment

Part 1 : Nuclear Fission and Context of Nuclear Data

slide-7
SLIDE 7

How to measure Spin Distribution ?

𝑍

𝑢ℎ 𝐵, 𝑎, 𝐹∗, 𝐾𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹∗ 𝐵,𝑎 × 𝑄 𝐾𝜌 𝐵,𝑎,𝐹∗

Séminaire Doctorant, LPSC, Juin 2014

7 Neutrons Statistical

(prompt γ) Spin(J)

Excitation Energy (MeV)

6

10 Discrete 𝜹 emission

States filled by fission

5 15

3 9

To study Spin distribution, look at 𝛿𝑞𝑠𝑝𝑛𝑞𝑢, 𝑜𝑞𝑠𝑝𝑛𝑞𝑢 structure effect at low excitation energy : Isomeric Ratio Isomer : state with longer half-life than neighboring states

Part 1 : Nuclear Fission and Context of Nuclear Data

Isomer

slide-8
SLIDE 8

𝑍

𝑢ℎ 𝐵, 𝑎, 𝐹∗, 𝐾𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹∗ 𝐵,𝑎 × 𝑄 𝐾𝜌 𝐵,𝑎,𝐹∗

Séminaire Doctorant, LPSC, Juin 2014

8 Fragment detection (A,Z,Ekin)

TOF

 B

Gas-filled

𝛿/n detectors

𝑄 𝑂𝑗𝑡𝑝𝑛𝑓𝑠 𝑂𝐻𝑇

𝐵,𝑎,𝐹𝑙

  • Isomeric ratio : Recent measurements on Lohengrin

Min/s Isomers : 𝐽,

136

𝑇𝑐,

132

𝑇𝑐,

130

𝑇𝑐,

129

𝑇𝑜,

129

𝑂𝑐,

99

𝑍

98

µs Isomers : 𝑌𝑓,

136

𝑈𝑓,

132

𝑇𝑐,

129

𝑍,

99

𝑍,

98

𝑍,

94

𝐶𝑠

88

ns Isomers : Almost all isotopes in heavy mass region 𝑄 𝛿𝑞𝑠𝑝𝑛𝑞𝑢

𝐵,𝑎,𝐹∗

How to measure Spin Distribution ?

Part 1 : Nuclear Fission and Context of Nuclear Data

slide-9
SLIDE 9

𝑍

𝑢ℎ 𝐵, 𝑎, 𝐹∗, 𝐾𝜌 = 𝑍 𝐵 × 𝑄 𝑎 𝐵 × 𝑄 𝐹∗ 𝐵,𝑎 × 𝑄 𝐾𝜌 𝐵,𝑎,𝐹∗

Séminaire Doctorant, LPSC, Juin 2014

9

  • FIPPS (Fission Product Prompt gamma-ray Spectrometer) Goals :
  • Direct measurement of prompt particles ( 𝛿𝑞𝑠𝑝𝑛𝑞𝑢, 𝑜𝑞𝑠𝑝𝑛𝑞𝑢)
  • Fission product spectroscopy (astrophysics interest)
  • Neutron emission
  • Short lifetime isomers (ps,ns)

Fragment detection (A,Z,Ekin)

TOF

 B

Gas-filled

𝛿/n detectors

𝑄 𝑂𝑗𝑡𝑝𝑛𝑓𝑠 𝑂𝐻𝑇

𝐵,𝑎,𝐹𝑙

  • Isomeric ratio : Recent measurement on Lohengrin

Min/s Isomers : 𝐽,

136

𝑇𝑐,

132

𝑇𝑐,

130

𝑇𝑐,

129

𝑇𝑜,

129

𝑂𝑐,

99

𝑍

98

µs Isomers : 𝑌𝑓,

136

𝑈𝑓,

132

𝑇𝑐,

129

𝑍,

99

𝑍,

98

𝑍,

94

𝐶𝑠

88

ns Isomers : Almost all isotopes in heavy mass region 𝑄 𝛿𝑞𝑠𝑝𝑛𝑞𝑢

𝐵,𝑎,𝐹∗

How to measure Spin Distribution ?

Part 1 : Nuclear Fission and Context of Nuclear Data

slide-10
SLIDE 10
  • Nuclear fission and usefulness of nuclear data for applications and

fundamental physics

  • Development of a new spectrometer : Gas

Filled Magnet (GFM)

  • Properties of a GFM : experimental outcome
  • Comparison with a Monte Carlo Calculation
  • Isomeric Ratio measurements at Lohengrin (ILL)

Séminaire Doctorant, LPSC, Juin 2014

10

Outline

slide-11
SLIDE 11

Lohengrin : selection with the mass over ionic charge ratios 𝐵

𝑟 and

Kinetic energy over Ionic charge 𝐹𝑙

𝑟

(A1,E1,q1)≡ (A2,E2,q2) ≡(A3,E3,q3) Limits :

  • 2 µs time of flight (TOF) → no prompt particle study (10−16 s)

Utility for GFM study :

  • Fission Fragment Source !!

IC

A1; A2; A3

 BRED

11

Back to the present : Lohengrin limits

Séminaire Doctorant, LPSC, Juin 2014 Part 2 : GFM Development

slide-12
SLIDE 12

Setup : The RED magnet is now filled with various gases → GFM GFM : Spatial dispersion of fission fragments according to the mass A and Nuclear charge Z Goal : Study of properties of this device / feasibility IC

𝑩𝟑

 BGFM Ionisation Chamber

12

Experimental Setup for GFM study

𝐶𝜍 ∝ 𝐵 𝑤 𝑨 𝑟 𝑎

𝑄,𝐻𝑏𝑡

𝐶𝜍 ∝ 𝐵 𝑎

1 3

[1]

Séminaire Doctorant, LPSC, Juin 2014 Part 2 : GFM Development

slide-13
SLIDE 13

Séminaire Doctorant, LPSC, Juin 2014

13

GFM separation power

Part 2 : GFM Development

IC

𝑩𝟑

 BGFM Ionisation Chamber

slide-14
SLIDE 14

Gas Comparison : Experimental results

Gas Pressure Electronic density ratio Resolution 𝑂2 7 mbar 1 2,2 % He 40 mbar 0,82 2,1 % 𝐵𝑠 − 𝐷𝐼4 8,5 mbar 1,5 3,0 %

Séminaire Doctorant, LPSC, Juin 2014

14

𝑄

Part 2 : GFM Development

𝐸𝑓𝑜𝑡𝑗𝑢𝑧 = 𝜍𝑓− 𝜍𝑓− 𝑂2, 𝑄 = 7𝑛𝑐𝑏𝑠

0,005 0,01 0,015 0,02 0,025 0,03 0,035 0,04 0,5 1 1,5 2

Magnetic resolution Density (arbitrary unit)

Evolution of the magnetic resolution with density in several gases for A=98

N2 He Ar-CH4 Y98 (N2)

  • Poly. (N2)
slide-15
SLIDE 15

Monte Carlo Calculation Architecture

Initial Condition:

Position/Velocity/Ionic charge/Magnetic Field

Trajectory inside GFM :

  • Effective charge : 𝑟𝑓𝑔𝑔
  • Charge changing

probability

  • Solution of motion

equation

  • Energy loss calculation
  • Straggling effect

Exit Condition:

Is the particle detected? = 𝑦, 𝑧 ∈ Ionization Chamber

Séminaire Doctorant, LPSC, Juin 2014

15

Part 2 : GFM Development

slide-16
SLIDE 16

16

Séminaire Doctorant, LPSC, Juin 2014

Gas Filled Magnet : What to compare

Part 2 : GFM Development

We will compare 𝐶 along the pressure

slide-17
SLIDE 17

17

Séminaire Doctorant, LPSC, Juin 2014

𝑶𝟑 Gas Filled Magnet : Test

98Y & A=98 / E=90MeV / 233U

𝑁𝐷𝐷 ± 1𝜏𝐶

𝜏𝐶 : beam width

B (Gaus)

Preliminary results

Part 2 : GFM Development

Big Three free parameters in 𝑂2

  • 𝑙 =

𝜏2𝑓− 𝜏𝑓− = 0,56 ± 0,05

  • 𝑟𝑓𝑔𝑔 = 𝑟𝐶𝑓𝑢𝑨 + 𝛾 ln

𝜍 𝜍0 → 𝛾 = −0,4

  • Δ𝑄 = P

meas − P MCC = 0,5 ± 0,3 mbar

Set using A=98 & 𝑍

98 experimental data

10 20 30 40 50 60 70 80 90 5 10 15

ΔEgaz

Pressure (mbar)

Energy loss in GFM for Mass 98 @ E=90MeV

July 2012 Experiment Monte Carlo Calculation

slide-18
SLIDE 18

18

Séminaire Doctorant, LPSC, Juin 2014

  • Agreement for pressure below 10 mbar at 1𝜏
  • 𝑙 → 𝐶

shift

  • For 𝑄 > 10 𝑛𝑐𝑏𝑠 inconsistent calculation → Density effect on effective charge calculation

Predictive calculation for light mass at 1𝜏 Design the new spectrometer (find the better geometry)

𝑶𝟑 Gas Filled Magnet : Comparison

B (Gaus)

Preliminary results

E=95MeV / 235U

Part 2 : GFM Development

slide-19
SLIDE 19
  • Nuclear fission and usefulness of nuclear data for applications and

fundamental physics

  • Development of a new spectrometer : Gas Filled Magnet (GFM)
  • Properties of a GFM : experimental outcome
  • Comparison with a Monte Carlo Calculation
  • Isomeric Ratio measurements at Lohengrin

(ILL)

Séminaire Doctorant, LPSC, Juin 2014

19

Outline

slide-20
SLIDE 20

Experimental Set-Up : µs Isomer

Coincidence between ionization chamber and 𝛿 detectors Δ𝑈𝐻𝑏𝑢𝑓 = 10𝑈1 2 → Isomeric state measurement Total 𝛿 spectrum → GS

  • measurement. More difficult

For long live GS, loss by gas pumping → correction needed 𝜇𝐻𝑏𝑡 ≪ 𝜇𝛾

20

Part 3 : Isomeric Ratio Measurements Séminaire Doctorant, LPSC, Juin 2014

slide-21
SLIDE 21

𝐶𝑠

88

Results

Séminaire Doctorant, LPSC, Juin 2014

21

Isomeric Ratio : 𝑆𝐽 𝐹𝑙 =

𝑂𝑔( 𝐶𝑠)

88𝑛

𝑂𝑔( 𝐶𝑠)+𝑂𝑔( 𝐶𝑠)

88 88𝑛

= 0,34 ± 0,007

0,2 0,25 0,3 0,35 0,4 0,45 0,5 50 60 70 80 90 100 110 Ratio Kinetic Energy (MeV)

Ratio : Isomer/GS

𝑸 𝑭∗, 𝑲𝝆

𝐹∗ = 𝑔(𝐹𝑙) : models Measurement → 𝑄 𝐹∗, 𝐾𝜌 𝐹𝑙

Fission : 𝜏𝐹𝑙 = 4 𝑁𝑓𝑊 Target : 𝜏𝐹𝑙 = 10 𝑁𝑓𝑊

𝐹𝑙 A

Part 3 : Isomeric Ratio Measurements

slide-22
SLIDE 22
  • Allow to separate isomeric state and GS feeding from a same 𝛿 line

Masse Isotope Period 𝜹

136

mI

I Xe 46,9 s 83,4 s 2,95 µs

197/381/1313/369 1313/1321/2289/ 197/381/1313

130

mSb

Sb 6,3 m 39,5 m

839/793/182/1017 793/839/330/182

132

mSb

Sb Te 4,10 m 2,79 m 28,1 µs

974/697/103/150 974/697/103/989 974/697/103/150

22

Séminaire Doctorant, LPSC, Juin 2014

Up view Side view

Beam Cut Method

Part 3 : Isomeric Ratio Measurements

slide-23
SLIDE 23

Nanosecond Isomer

Séminaire Doctorant, LPSC, Juin 2014

23

Structure effect will deform the ionic charge distribution

18,68126485 1,96827205

Nikolaev and D. (1968) (2)

Part 3 : Isomeric Ratio Measurements

slide-24
SLIDE 24

Conclusion and Perspectives

GFM studies

  • Nowadays :
  • Spectrometer power is bound by the atomic collision in gas

𝜏𝐶 𝐶 = 𝜏𝐵 𝐵 ≥ 1,5% ( A 𝜏𝐵 = 66)

  • Good understanding of physics inside a GFM
  • Future:
  • Benchmark between MCC and Geant4
  • Design the FIPPS spectrometer with a validated code
  • Experiment with different gas

Fission yields and spin distribution

  • New methods has been developed
  • New observables
  • Goals : Improvement of fission models
  • Future :
  • Comparison with theoretical code
  • Analysis …
  • New Experiment

Séminaire Doctorant, LPSC, Juin 2014

24

slide-25
SLIDE 25

Thank you for you attention Any questions?

Séminaire Doctorant, LPSC, Juin 2014

25

slide-26
SLIDE 26

Backup

Séminaire Doctorant, LPSC, Juin 2014

26

slide-27
SLIDE 27

 Impact of fission yields on the current and innovative fuel cycles 𝑍 𝐵, 𝑎, 𝐹∗, 𝐾𝜌 = 𝑍 𝐵, 𝑎 × 𝑄(𝐹∗, 𝐾𝜌)

  • Inventory of spent fuel

Isotopic composition → Residual power

𝑆𝑄 𝑢 = 𝑍 𝐵, 𝑎 𝐹𝛾 𝐵, 𝑎 𝜇

𝑎

(𝐵, 𝑎)

  • Radiotoxicity of spent fuel

Context of the fission yield studies

27

Séminaire Doctorant, LPSC, Juin 2014

Uncertainty of residual power calculation come from the uncertainty of fission yields 𝑍 𝐵, 𝑎

Part 1 : Nuclear Fission and Context of Nuclear Data

slide-28
SLIDE 28
  • Atomic collision model at each step x according to M.Paul & H.Betz :
  • Equilibrium charge state distribution : 𝐺 𝑟 ∝ exp − 𝑟−𝑟

2𝑒2

  • 𝜏𝑢𝑝𝑢

𝑑𝑏𝑞𝑢 using experimental measurements : with F(q) we can define 𝐵𝑑, 𝑐𝑑, 𝐵𝑚, 𝑐𝑚

  • Total Loss cross section : 𝜏𝑢𝑝𝑢

𝑚𝑝𝑡𝑡(𝑟) = 𝐵𝑚 exp −𝑐𝑚 𝑟 − 𝑟

  • Total Capture cross section : 𝜏𝑢𝑝𝑢

𝑑𝑏𝑞𝑢(𝑟) = 𝐵𝑑 exp 𝑐𝑑 𝑟 − 𝑟

  • Multiple Capture cross section : negligible
  • Multiple Loss cross section : 𝜏2𝑚 = 𝑙0𝜏𝑚

(Heavy gas)

  • For 𝑂2, 𝒍𝟏 =

𝝉𝟑𝒎 𝝉𝒎 ≈ 𝟏, 𝟔

  • The probability for charge changing

through a distance x,

  • 𝑄 𝑟, 𝑟′ =

𝜏 𝑟,𝑟′ 𝜏𝑢𝑝𝑢𝑏𝑚

1 − 𝑓−𝜏𝑢𝑝𝑢𝑏𝑚𝜍𝑦

Model involved into the MCC

28

  • M. Paul et al, Nuclear Instruments and Methods in Physics Research A, vol. 277, pp. 418-430, 1989

H.D. Betz, Reviews of Modern Physics, vol.44, n° 3, p. 465, July 1972. Séminaire Doctorant, LPSC, Juin 2014

slide-29
SLIDE 29

Model involved into the MCC

  • According to Pierce, the energy loss,
  • 𝑒𝐹

𝑒𝑌 𝑎𝑗𝑝𝑜,𝐵,𝐹 = 𝑟𝑓𝑔𝑔

2

𝛿𝑞

2 ×

𝑒𝐹 𝑒𝑌 𝑞,𝐹

𝐵

screening effect

  • According to Betz,
  • 𝑟𝑓𝑔𝑔 = 𝑎𝑗𝑝𝑜 1 − 𝐷 × exp −

𝑤𝑗𝑝𝑜 𝑤0𝑎𝜀

  • 𝐷 = 1,032 ; 𝜀 = 0,69 ; 𝑤0 = 2,19.10−8 𝑑𝑛. 𝑡−1 : Bohr velocity
  • F(q) is symmetric → 𝒓𝒇𝒈𝒈 ≡ 𝒓
  • According to Gregorich, the charge density effect,
  • Δ𝑟

∝ ln

𝜍 𝜍0

∝ ln

𝑄 𝑄0

  • 𝒓𝒇𝒈𝒈 = 𝒓𝒇𝒈𝒈𝑪𝒇𝒖𝒜 + 𝜸 × 𝐦𝐨

𝑸 𝑸𝟏 with 𝜸 = −𝟏, 𝟓

  • Straggling effect : Molière potential

Séminaire Doctorant, LPSC, Juin 2014

29

time µs ns ps 𝐹∗ 𝑓− Pierce et al, Physical Review, vol 173, number 2, pp 390-405, 1968 K.E. Gregorich, Nuclear Instruments and Methods in Physics Research A, vol. 711, pp. 47-59, 2013.

slide-30
SLIDE 30

Charge Density Effect

Séminaire Doctorant, LPSC, Juin 2014

30

time µs ns ps 𝐹∗ 𝑓−

After a capture or a loss of an 𝑓−, the ion can be excited, The relaxation time can be longer than the collision time. Cross section of an excited state ≠ Cross section of the GS

slide-31
SLIDE 31

Measurement of the Energy Loss in the GFM

31

Calibration : Input SRIM inside foils

Efinal = 𝐹𝑗𝑜𝑗𝑢 − Δ𝐹

𝑔𝑝𝑗𝑚1 𝐹𝑗𝑜𝑗𝑢, 𝑎, 𝐵

− Δ𝐹

𝑔𝑝𝑗𝑚2(𝐹𝑗𝑜𝑗𝑢 − Δ𝐹 𝑔𝑝𝑗𝑚1, 𝑎, 𝐵)

Result : Need SRIM in the second foil

Efinal = 𝐹𝑗𝑜𝑗𝑢 − Δ𝐹

𝑔𝑝𝑗𝑚1 𝐹𝑗𝑜𝑗𝑢, 𝑎, 𝐵

− Δ𝐹𝑕𝑏𝑡 𝐹, qeff, Z, A − Δ𝐹

𝑔𝑝𝑗𝑚2(𝐹𝑗𝑜𝑗𝑢 − Δ𝐹 𝑔𝑝𝑗𝑚1

− Δ𝐹𝑕𝑏𝑡, 𝑎, 𝐵)

Since we are interested in Δ𝐹𝑕𝑏𝑡, the sensitivity of the foil layer is small

Séminaire Doctorant, LPSC, Juin 2014

slide-32
SLIDE 32

GFM @Lohengrin

  • Isobaric beam could allow to measure the Total 𝛾, 𝛿 decay energy per mass

32

Séminaire Doctorant, LPSC, Juin 2014

slide-33
SLIDE 33

Séminaire Doctorant, LPSC, Juin 2014

33

slide-34
SLIDE 34

Symmetry contamination

Séminaire Doctorant, LPSC, Juin 2014

34

1000 2000 3000 4000 5000 6000 7000 8000 13 18 23 28

Counts (arbitrary unit) Ionic charge

Ionic charge distribution of the mass 124 with an indicator of contamination

1000 2000 3000 4000 5000 14 19 24 29

Count (arbitrary unit) Ionic charge

Shape of the ionic charge distribution of the mass 124 by removing the artefact

slide-35
SLIDE 35

Beam Cut Method

  • Temps d’acquisition ~ 5𝑈1 2
  • Répétition → ↗ stat
  • Séparation état métastable/ fondamental (peuplant une même raie)

Masse Isotope Durée de vie Raie

136

mI

I Xe 46,9 s 83,4 s 2,95 µs

197/381/1313/369 1313/1321/2289/ 197/381/1313

130

mSb

Sb 6,3 m 39,5 m

839/793/182/1017 793/839/330/182

132

mSb

Sb Te 4,10 m 2,79 m 28,1 µs

974/697/103/150 974/697/103/989 974/697/103/150

35

Séminaire Doctorant, LPSC, Juin 2014

slide-36
SLIDE 36

Nanosecond Isomer

  • Stabilisation de la charge

moyenne dans la cible

  • Si nanosecondes

isomères :

  • Réarrangement du

cortège électronique

  • Distribution en charge

plus complexe

36

Café Scientifique 7 Novembre 2013

slide-37
SLIDE 37

Nanosecond Isomer

Séminaire Doctorant, LPSC, Juin 2014

37

18,68126485 1,96827205

Nikolaev and D. (1968) (2)

slide-38
SLIDE 38

Nanosecond Isomer

Séminaire Doctorant, LPSC, Juin 2014

38

15 20 25 30 35 40 137 138 139 140 141 142 143 144 145 146 147

Charge ionique déconvoluée

Masse / Isotopes

  • D. Betz (1983) (3)

Nikolaev and D. (1968) (2) q3 q2 q1

slide-39
SLIDE 39

Interpretation using theoretical code

Fifrelin/ Statistical Model…

Isomeric Ratio : Experimental measurements Number of µs isomer state filled by fission Number of GS filled by fission Comparison 𝑄 𝐹∗ 𝑎 × 𝑄 𝐾𝜌 𝐹∗

𝑛𝑝𝑒𝑓𝑚𝑡

Fifrelin is a Monte Carlo code developed by CEA Cadarache. Calculation of gamma decay of fission fragments.

Séminaire Doctorant, LPSC, Juin 2014

39

Part 3 : Isomeric Ratio Measurements

slide-40
SLIDE 40

Séminaire Doctorant, LPSC, Juin 2014

40

𝑈𝑓

132

slide-41
SLIDE 41

What about FIPPS

GFM Workshop, ILL , May 2013

41

Parallel Beam @ 𝐹 = 90 MeV 1 cm collimator (in & out)

Great separation ≅ 𝟔 𝑵𝒃𝒕𝒕

Part 2 : Développement d'un GFM

Goal : Find a geometry with the better mass separation 𝜏𝐻𝐺𝑁 < 𝜏

𝑔𝑗𝑡𝑡𝑗𝑝𝑜 Mass resolution is ruled

by fission process 𝜏𝐻𝐺𝑁 > 𝜏

𝑔𝑗𝑡𝑡𝑗𝑝𝑜 Convolution between

GFM and fission mass resolution

slide-42
SLIDE 42

𝐶𝑠

88

Results

0,00 200000,00 400000,00 600000,00 800000,00 1000000,00 1200000,00 40 60 80 100 120 Counts (arbitrary unit) Kinetic Energy (MeV)

Isomer Count rate evolution with energy

110,9 159,1 Moyenne

Isomeric Ratio : 𝑆𝐽 = 𝑂

𝑔(

𝐶𝑠)

88𝑛

𝑂

𝑔(

𝐶𝑠) + 𝑂

𝑔(

𝐶𝑠)

88 88𝑛

= 0,34 ± 0,007

0,2 0,25 0,3 0,35 0,4 0,45 0,5 50 60 70 80 90 100 110 Ratio Kinetic Energy (MeV)

Ratio : Isomer/GS

Séminaire Doctorant, LPSC, Juin 2014

42

Part 3 : Mesures de rapports isomériques

𝑂𝛿1 = 𝑂

𝑔𝜗𝛿1𝐽𝛿1

𝑂𝛿2 = 𝑂

𝑔𝜗𝛿2𝐽𝛿2

Perfect agreement between 𝛿1 & 𝛿2

0,00 500000,00 1000000,00 1500000,00 2000000,00 2500000,00 3000000,00 3500000,00 4000000,00 4500000,00 40 60 80 100 120 Count (arbitrary unit) Kinetic Energy (MeV)

GS Count rate evolution with energy

775,28 802,14 Moyenne

Contamination :(_^97)𝑇𝑠

slide-43
SLIDE 43

𝐶𝑠

88

Analysis : 𝛿 efficiency

Without TrueCoinc

slide-44
SLIDE 44

The Lohengrin mass spectrometer

𝑪 𝑭 𝑩 𝒓 𝑭𝒍 𝒓 Target Detector(s) 𝑭𝒍

′

𝒓 𝑩 𝒓

′

Séminaire Doctorant, LPSC, Juin 2014

44

Part 2 : Développement d'un GFM

slide-45
SLIDE 45

45

Séminaire Doctorant, LPSC, Juin 2014

𝑶𝟑 Gas Filled Magnet : Test

98Y & A=98 / E=90MeV / 233U

𝑁𝐷𝐷 ± 1𝜏𝐶

𝜏𝐶 : beam width

  • 𝜏𝑁𝐷𝐷 =

𝜏𝐶

𝑡𝑢𝑏𝑢 2

+ 𝜏𝑡𝑧𝑡𝑢

2

→ Systematic : Geometry/Temperature/Library/Target

  • For 𝑄 > 10 𝑛𝑐𝑏𝑠 inconsistent calculation → Density effect on effective charge calculation

B (Gaus)

Preliminary results

Part 2 : Développement d'un GFM

Parameter Sensibility 𝑪 Sensibility 𝝉𝑪 𝚬𝐅𝐡𝐛𝐭 𝜄0 → 𝜄0 + 1° 0,346 0,711 0,44 𝜄0 → 𝜄0 − 1° 0,395 0,855 0,44 𝜄1 → 𝜄1 + 1° 0,040 0,231 0,003 𝜄1 → 𝜄1 − 1° 0,033 0,174 0,004 𝑆𝑝𝑣𝑢 → 𝑆𝑝𝑣𝑢 + 5 𝑛𝑛 0,00059 0,0510 𝑆𝑝𝑣𝑢 → 𝑆𝑝𝑣𝑢 − 5 𝑛𝑛 0,00088 0,0430 𝑆𝑗𝑜 → 𝑆𝑗𝑜 + 5 𝑛𝑛 0,00096 0,0183 𝑆𝑗𝑜 → 𝑆𝑗𝑜 − 5 𝑛𝑛 0,00058 0,0202 𝑈 → 𝑈 + 10 𝐿 0,00236 0,055 𝑈 → 𝑈 − 10 𝐿 0,00241 0,058 Library (Jeff vs ENDF) 0,00020 0,0028 Target 𝑉

233 𝑤𝑡

𝑉

235

0,00424 0,0097 0,006 𝑙 → 𝑙 ± 0,05 0,063 0,063 SRIM 0,0018 0,024 0,059