Preliminary results of n f measurements at cern n tof with fic0 and fic1 detectors
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Preliminary Results of (n,f) Measurements at CERN n_TOF with FIC0 and FIC1 Detectors. P.Cennini 1 , A.Goverdovski 2 , W.Furman 3 , V.Ketlerov 2,1 , V.Konovalov 3,1 , V.Vlachoudis 1 1 CERN, 2 IPPE, 3 JINR and n_TOF Collaboration. With a lot of help of:. A.Doroshenko 2 S.Girod 1

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Preliminary results of n f measurements at cern n tof with fic0 and fic1 detectors

Preliminary Results of (n,f) Measurements at CERN n_TOF with FIC0 and FIC1 Detectors

P.Cennini1,

A.Goverdovski2,

W.Furman3,

V.Ketlerov2,1,

V.Konovalov3,1,

V.Vlachoudis1

1CERN, 2IPPE, 3JINR

and n_TOF Collaboration


With a lot of help of
With a lot of help of: FIC0 and FIC1 Detectors

A.Doroshenko2

S.Girod1

D.Kolokolov2

V.Mitrofanov2

B.Samylin2

M.Sedysheva3

1CERN, 2IPPE, 3JINR


Motivation
Motivation FIC0 and FIC1 Detectors

n_TOF Collaboration scientific program

Nuclear data for ADS:

fission cross-section measurements

Fundamental nuclear physics:

study of vibrational fission resonances


Fast ionization chamber design
Fast Ionization Chamber Design FIC0 and FIC1 Detectors

  • Gas – Ar 90%+CF4 10%

  • Pressure – 600 mbar

  • Distance – 5 mm

  • HV – 300 V

  • 17 targets in the beam

  • “noise” electrode

  • 2 targets out of the beam


Fic1 photo
FIC1 Photo FIC0 and FIC1 Detectors


Fic1 and fic0 photo
FIC1 and FIC0 Photo FIC0 and FIC1 Detectors


Inside fic1 photo 1
Inside FIC1 Photo 1 FIC0 and FIC1 Detectors


Inside fic1 photo 2
Inside FIC1 Photo 2 FIC0 and FIC1 Detectors


Fic0 main electronics
FIC0 Main Electronics FIC0 and FIC1 Detectors


Basic equations
Basic Equations FIC0 and FIC1 Detectors

For single channel i of given isotope X

TDC data

Flash ADC data

If there is some impurity nucleus Y


Extraction of cross section
Extraction of cross-section FIC0 and FIC1 Detectors

Flash ADC data

Kiis obtained from MC simulation

is calculated with accounting for dead time and

from an analysis of pulse-height histogram

is really measured (see below for more detail)

From reference 235U channel one can extract F(E(t))

So it is possible to extract fission cross-section

from counting rate of each (X,i) channel


Isotopic dilution method
Isotopic Dilution Method FIC0 and FIC1 Detectors

Definitions:

m5 , m6 – masses of 235U and 236U targets

 - content of 235U in 236U target

5, 6 – fission cross-sections

5, 6– registration efficiencies of FF

(6 is valid for FF from 235U admixture to 236U target!)

n5, n6 – count rates


Isotopic dilution method1
Isotopic Dilution Method FIC0 and FIC1 Detectors

  • Master equation

  • R = n6 / n5 = (6/5)(m66 +  m65)/ (m55)

  • Around resolved resonances En=8 – 20 eV 5 is very high

  • (up to 710 b) while 6 = 0, then

  • R0 =  (m66)/( m55 )

  • For other energies where 5 << 6 and due to  << 1

  • R(En) = R0 (6 / 5 )/ 

  • There are no 6,5 or m6 , m5 ratios. We have only  and count rates.

  •  = 0.00047 ± 0.00002 – measured by mass-spectrograph


  • Isotopic dilution method2
    Isotopic Dilution Method FIC0 and FIC1 Detectors

    U-235, 0.047%


    List of targets
    List of Targets FIC0 and FIC1 Detectors

    ----FIC0----

    235U - 47mg (3 targets)

    238U - 110mg (3 targets)

    232Th - 80mg (2 targets)

    236U - 20mg (2 targets)

    237Np - 10mg (1 target)

    234U - 34mg (6 targets)

    ----FIC1----

    235U - 30mg (1 targets)

    238U - 90mg (2 targets)

    241Am - 2mg (4 targets)

    243Am - 10mg (4 targets)

    245Cm - 2mg (2 target)

    233U - 20mg (2 targets)


    Targets
    Targets FIC0 and FIC1 Detectors

    Backing - 100 microns aluminum foil

    Substance is painted on both sides

    Spot diameter is 80mm

    Thickness from 5mkg/cm2 to 450mkg/cm2

    Number of painted layers 100-200

    Uniformity is 5% - 10%


    Painting technique
    Painting Technique FIC0 and FIC1 Detectors


    Target analysis
    Target analysis FIC0 and FIC1 Detectors

    For mass, impurities, uniformity with

    Ionization chamber with Frisch grid

    For low radioactive targets

    232Th, 238U, 235U, 237Np, 236U

    Si detector

    For high radioactive targets

    233U, 245Cm, 243Am, 241Am


    Ionization chamber
    Ionization Chamber FIC0 and FIC1 Detectors


    Alpha spectrum of 235 u
    Alpha Spectrum of FIC0 and FIC1 Detectors235U


    Alpha spectrum of 232 th
    Alpha Spectrum of FIC0 and FIC1 Detectors232Th


    Si detector
    Si Detector FIC0 and FIC1 Detectors

    S = 1 cm2


    Alpha spectrum of 241 am
    Alpha Spectrum of FIC0 and FIC1 Detectors241Am


    Alpha spectrum of 243 am
    Alpha Spectrum of FIC0 and FIC1 Detectors243Am

    (2.6%)


    Alpha spectrum of 245 cm
    Alpha Spectrum of FIC0 and FIC1 Detectors245Cm


    Alpha spectrum of 237 np
    Alpha Spectrum of FIC0 and FIC1 Detectors237Np


    235 u contamination
    235 FIC0 and FIC1 DetectorsU Contamination

    Even impurity of 10e-5 – 10e-4

    which is impossible to determine by a-analysis

    is essential for neutron induced fission experiments


    235 u contamination of 236 u and 238 u
    235 FIC0 and FIC1 DetectorsU Contamination of 236U and 238U

    1e-5 of 235U

    238U

    236U

    4e-4 of 235U

    235U


    Noise filtering 238 u
    Noise Filtering FIC0 and FIC1 Detectors238U


    Noise filtering 237 np
    Noise Filtering FIC0 and FIC1 Detectors237Np


    Noise filtering low energy
    Noise Filtering (Low Energy) FIC0 and FIC1 Detectors


    Noise filtering 237 np res
    Noise Filtering FIC0 and FIC1 Detectors237Np (res)


    Neural network filtering
    Neural Network Filtering FIC0 and FIC1 Detectors


    Pulse height histogram 236 u
    Pulse Height Histogram FIC0 and FIC1 Detectors236U


    T e calibration from capture
    T-E Calibration from Capture FIC0 and FIC1 Detectors


    235u resonances
    235U Resonances FIC0 and FIC1 Detectors


    T e calibration from fission
    T-E Calibration from Fission FIC0 and FIC1 Detectors


    Energy resolution 234 u
    Energy Resolution FIC0 and FIC1 Detectors234U


    Preliminary results below 1mev
    Preliminary Results Below 1MeV FIC0 and FIC1 Detectors

    234U, 236U

    237Np, 245Cm


    237 np resonances 1
    237 FIC0 and FIC1 DetectorsNp Resonances 1


    237 np resonances 2
    237 FIC0 and FIC1 DetectorsNp Resonances 2


    237 np resonances 3
    237 FIC0 and FIC1 DetectorsNp Resonances 3


    237 np resonances 4
    237 FIC0 and FIC1 DetectorsNp Resonances 4

    present

    ENDF pointwise


    237 np resonances 5
    237 FIC0 and FIC1 DetectorsNp Resonances 5


    245 cm with a background
    245 FIC0 and FIC1 DetectorsCm with a-background


    245 cm
    245 FIC0 and FIC1 DetectorsCm


    245 cm resonances 1
    245 FIC0 and FIC1 DetectorsCm Resonances 1


    245 cm resonances 2
    245 FIC0 and FIC1 DetectorsCm Resonances 2


    245 cm resonances 3
    245 FIC0 and FIC1 DetectorsCm Resonances 3


    234 u resonances 1
    234 FIC0 and FIC1 DetectorsU Resonances 1


    234 u resonances 2
    234 FIC0 and FIC1 DetectorsU Resonances 2


    234 u resonances 3
    234 FIC0 and FIC1 DetectorsU Resonances 3


    234 u resonances 4
    234 FIC0 and FIC1 DetectorsU Resonances 4


    234 u resonances 5
    234 FIC0 and FIC1 DetectorsU Resonances 5


    234 u resonances 6
    234 FIC0 and FIC1 DetectorsU Resonances 6


    234 u vibrational resonances
    234 FIC0 and FIC1 DetectorsU Vibrational Resonances


    236 u resonances 1
    236 FIC0 and FIC1 DetectorsU Resonances 1


    236 u resonances 2
    236 FIC0 and FIC1 DetectorsU Resonances 2


    236 u resonances 3
    236 FIC0 and FIC1 DetectorsU Resonances 3


    236 u 235 u ratio
    236 FIC0 and FIC1 DetectorsU/ 235U Ratio


    Present status of data analysis
    Present Status of Data Analysis FIC0 and FIC1 Detectors

    Flash ADC raw data analysis with neural network

    TDC and FADC data comparison and adjustment

    T-E calibration for En>0.5MeV

    Completion of full MC simulation

    Neutron flux determination

    Extraction of neutron induced fission cross-sections


    Thank you very much
    Thank You Very Much FIC0 and FIC1 Detectors

    Good luck!


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