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MetroFission WP 5: Nuclear Decay Data. DEVELOPMENT OF BETA SPECTROMETRY USING CRYOGENIC DETECTORS. M. Loidl , C. Le-Bret, M. Rodrigues, X. Mougeot CEA Saclay – LIST / LNE, Laboratoire National Henri Becquerel, France. METALLIC MAGNETIC CALORIMETERS: ONE TYPE OF CRYOGENIC DETECTORS.

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development of beta spectrometry using cryogenic detectors

MetroFission

WP 5: Nuclear Decay Data

DEVELOPMENT OF BETA SPECTROMETRY USING CRYOGENIC DETECTORS

M. Loidl, C. Le-Bret, M. Rodrigues, X. Mougeot

CEA Saclay – LIST / LNE,

Laboratoire National Henri Becquerel, France

metallic magnetic calorimeters one type of cryogenic detectors
METALLIC MAGNETIC CALORIMETERS:ONE TYPE OF CRYOGENIC DETECTORS

Thermal detectors:

DT = E/C

Paramagneticthermometer

DTDM

SQUID magnetometer

DMDV

Thermal link

td = C/G

Verylowtemperature (10 – 20 mK) :

C T(metalsatverylowT)

DT = E/C

thermodynamic

fluctuation noise

sE kBT 2C

td = C/G

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

metallic magnetic calorimeters for beta spectrometry
METALLIC MAGNETIC CALORIMETERS FOR BETA SPECTROMETRY

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Source embedded inside the detector absorber

4p sr solid angle

no back-scattering at the detector surface

energy loss of beta particles in the source:

energy should be detected anyway

  • Determination of the absorber dimensions by Monte Carlo simulation
  • detection efficiency close to 100 %
  • Very low T low thermodynamic fluctuation noise
  • high energy resolution
  • low energy threshold

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

ni 63 theoretical spectrum
Ni-63: THEORETICAL SPECTRUM
  • Allowed transition: Theoretical spectrum can be calculated with high degree of
  • confidence validate measurement method by comparison experiment - theory
  • Exchange effect(creation of beta electron into a bound orbital; simultaneous emission of a
  • bound electron) has been included in the code BetaShape developed at LNHB

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

n i 63 spectrum measured using dried sources
Ni-63: spectrummeasuredusingdried sources

Sources made by drying

a drop of NiCl2 solution

Experimental spectra differ from

one another and from theory

Agreement with theory better

when including exchange effect

No clear influence of

- carrier concentration (MD8)

- absorber material (MD11)

Part of energy in NiCl2

metastable states

detection of b energy

incomplete?

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

n i 63 electroplated sources 1
Ni-63: electroplated sources (1)
  • Requirements:
  • metallic Ni deposit
  • activity / surface ~ 100 Bq / mm2
  • minimize quantity of inactive Ni
  • electrolyte containing a small
  • Ni concentration

Nickel chloride concentration [mol/L] 0.01

Hypophosphite ion concentration [mol/L] 0.25

Acetic acid concentration [mol/L] 0.5

Mass activity [kBq/g] 67.5

Anode material Pt

Cathode material Au

Temperature [°C] 70

Current density [mA/mm2] 2 - 5

Deposition time [min] 2

Activity per unit surface [Bq/mm2] 274

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

n i 63 electroplated sources 2
Ni-63: electroplated sources (2)
  • Energy threshold: 200 eV
  • Energy resolution: 51 eV (FWHM) @ 59.5 keV
  • Excellent agreement experiment - theory
  • when taking account of exchange effect
  • Confirmation of the calculation of the
  • exchange effect in the code BetaShape
  • (developed at LNHB)

241Am 59.5 keVgline

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

n i 63 electroplated sources 3
Ni-63: electroplated sources (3)

Au / Ag absorbers:

no influence of the absorber material

Counts / 100 eV

Ag Ka escape peak

241Am 59.5 keVgline

Au absorber

Ag absorber

Theory w. exchange effect

Energy (keV)

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

measurement of a forbidden beta spectrum of low maximum energy pu 241

MEASUREMENT OF AFORBIDDEN BETA SPECTRUM OF LOW MAXIMUM ENERGY:Pu-241

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

pu 241 spectrum measured with a dried source 1
Pu-241: SPECTRUM MEASURED WITH A DRIED SOURCE(1)

Good agreement between

experiment and theory

starting from ~ 7 keV

Discrepancy at low energies

First forbidden, non-unique

transition;

no shape factor used for

theoretical spectrum

discrepancy at low

energies due to

insufficiency of theory

or to

our detector / source?

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

pu 241 spectrum measured with a dried source 2
Pu-241: SPECTRUM MEASURED WITH A DRIED SOURCE(2)

Case of 241Pu:

very small error if calculated

as an allowed transition:

“x approximation” well fulfilled:

2x = aZ/2R > E0

Discrepancy at low energies

greatly reduced if the

exchange effect is taken into

account

Remaining discrepancy

most likely due to the use

of a dried source

>

| PAGE 12

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

study of absorbers for higher energy 1
STUDY OF ABSORBERS FOR HIGHER ENERGY (1)

Higher energy beta spectra:

Correction for energy loss by escape of Bremsstrahlung photons

from the detector must be considered.

Example:36Cl

Pure beta emitter; second forbidden non-unique transition

Emax = 709 keV

Au absorber thickness for stopping 709 keV electrons: 260 µm

Monte Carlo simulation:

36Cl source f = 300 µm enclosed inside a

Au cylinder f = 1 mm, thickness 2 x 260 µm

study of absorbers for higher energy 2
STUDY OF ABSORBERS FOR HIGHER ENERGY (2)

Input: theoretical spectrum of 36Cl

Output: simulated detected spectrum

Calculation of a correction function

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

conclusion and perspectives
Conclusion and perspectives
      • -
      • -
  • -

Metallic magnetic calorimeters are in an excellent position for

the precise measurement of the shapes of low energy beta spectra

Great influence of the type of beta source:

drop deposited sources: discrepant spectra

electroplated sources: reproducible spectra,

good agreement experiment – theory

promising alternative: source implantation into absorber

Higher energy beta spectra: correction for energy loss by escape of

photons from the detector must be considered

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013

metallic magnetic calorimeters for beta spectrometry 2
metallicmagneticcalorimetersfor beta spectrometry (2)

Linearity check using (external) 55Fe, 109Cd and 241Am sources

Experimental data points

Linear fit

fit uncertainty

Experimentalline positions [channels]

Residuals< fit uncertainty

(≤ 0.1 %);

No tendency

Tabulated line energy [keV]

ICRM 2013 | Antwerp, Belgium | 17-21 June 2013