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Neutron Detection with Diamond Detectors(252Cf source measurement)
� 2nd ADAMAS workshop ≺GSI Darmstadt, 15th-17st -December-2013
Jose Duenas, Luıs Acosta & Ismael Martel Dpto. Fısica Aplicada Universidad de Huelva.
Francisco Manchado & Pepe Sanchez Hostipal Juan Ramon Jimenez
Jose Duenas ([email protected]) Neutron detection with DD UHU Dpto. Fısica Aplicada 1 / 10
Motivation & Outline
1 Motivation.Identification of neutrons by means of n-C interaction.Neutron detection in Hospital environment.PhD thesis of Francisco Manchado.
2 Some typical neutron detectors.3 Experimental lab setup.
252Cf neutron source.Chamber + electronics setup.
4 Preliminary results.Low energy part (< 2 MeV).Contributions above 2 MeV.
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Neutron interactions with matter
Main interaction
Neutrons have not electriccharge (neutral), which makedirect detection a “bit” difficult.
Main interations: Scattering andabsorption.
Classic expression for kineticenergy v = 1.383× 107
√E .
3He, 235U and 10B commonlyused in detectors due to largeabsorption cross sections for theproduction of charged particleswith low-speed neutrons.
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Detectors for neutrons
Different types
Solid, liquid, or gas-filled media.
Some examples:
gas-filled (3He) counterscintillatorsfission chambers
Detectors with neutron-activematerial added:
Gadolinium.10B.6Li; thermal neutrons via(n,α) reaction.6LiF on diamond [M. Angelone et al.
NIMA 595 (2008) 616].
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252Cf neutron source
Spontaneous fission neutron source
Table: Main composition of the neutronsource (Oak Ridge National Lab).
Nuclide Mass % Activity %
249Cf 9.297 0.103250Cf 18.505 5.456251Cf 7.186 0.0309252Cf 65.012 94.412
Half line of 2.7 years.
Active diameter of 5 mm.
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Electronic chain setup
Lab setup
scCVD-500 µm; 4 mm × 4 mm; 300 V; leakage no readable (< 1 nA).
Mesytec MSI-8 preamplifier + shaper (1 or 2 µs shaping time).
Mesytec MHV high voltage supply and MNV for electronics bias.
Canberra 16K 1 µs ADC. USB interfase. GenieTM software.
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Chamber setup
In the chamber
Chamber to ambient pressureexcept for the α calibration.
Detector connected directly tothe lemo feedthrough.
Several Al layers around thechamber to avoid contaminationand also noise.252Cf source far from detector.
Thick lead shield (3.2 mm) justin front of the source to stop αparticles.
Measurement in dark.
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252Cf spectra for long term acquisition Low energy part
Spectrum time progression
energy (MeV)0.6 0.8 1 1.2 1.4 1.6 1.8 2
co
un
ts
0
2000
4000
6000
8000
10000
12000
42 days acquisition
21 days acquisition
1.5 days acquisition
Other spectrum from 252Cf,using a setup with a pcCVD anda Si for coincidence, see bottomright [S. Oberstedt NIMA 714 (2013) 31].
pulse hight (channel)0 50 100 150 200 250 300 350
co
un
ts
310
410
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252Cf spectra for long term acquisition Contributions above 2 MeV
Spectrum time progression
energy (MeV)0.6 0.8 1 1.2 1.4 1.6 1.8 2
co
un
ts
0
200
400
600
800
1000
1200 42 days acquisition
21 days acquisition
1.5 days acquisition
energy (MeV)3.5 4 4.5 5 5.5 6 6.5 7 7.5
co
un
ts
0
2
4
6
8
10
12
14
16
42 days acquisition
21 days acquisition
1.5 days acquisition
No found anything like it in literature, quite often 12C(n,α)9Be &T(d,n)4He at 14.8 MeV.
Could one of the contact layer (DLC/Pt/Au) interacting with n?
Need for n reaction simulation.
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Summary and future work
Summary
Characterization with 252Cf source.
Our scCVD-500 µm proved to be able to detect neutrons.
Also proved the stability behavior for 41 days nonstop measurement.
Near future
Simulation will be done to identify the possible reactions.
Experiment, propably at CNA accelerator Sevilla, with the rightreaction to produce neutrons.
Design the proper diamond detector (either fast or slow neutrons).
Study the integration of the system.
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