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IX International school-seminar: Actual problems of microworld physics Belarus, Gomel, July 23- August 3, 2007. Position-sensitive detectors of thermal neutrons: types, characteristics, applications. A.V. Churakov. FLNP JINR 2007. Neutron scattering methods. - PowerPoint PPT Presentation
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Position-sensitive detectors of thermal neutrons: types, characteristics, applications.
A.V. Churakov
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Belarus, Gomel, July 23- August 3, 2007Belarus, Gomel, July 23- August 3, 2007
FLNP JINR
2007
Neutron scattering methods
It is possible to study light elements and elements with close atomic numbers
Deep penetration into the sample – allow to explore in volume
Magnetic moment of neutron allow studies magnetic structure of the sample
Neutronsource
n nn
n
n
CollimatorDetectors
Sampleenvironment
and positioningsystems
Sample
Schematic view of the neutron scattering facility
Spectrum of the magneticSpectrum of the magnetic multilayer sample multilayer sample
measured at the refletometer REFLEXmeasured at the refletometer REFLEX
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Why PSD?Position-sensitive detectors allows to
observe not only the fact of the particles transit throughout the detector volume, but exact coordinate of the particle.
All spectrum can be measured in one experiment
Decrease the time of the experimentBecomes possible real-time measurements
and research dynamic of the processesand many other benefits
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Main characteristic of the PSD Spatial resolution Efficiency Count rate Active area (in some cases – angle range) Integral and differential nonlinearity Stability, reliability Sensitivity to γ-rays Capability to work in TOF mode Size and mass
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Registration of thermal neutrons
Neutron capture reactions, commonly used in neutron
detectors
n+3He → 3H+p+0,77 MeVn+6Li → 3H+α+4,79 MeVn+10B→7Li+α+γ(0,48 MeV)+2,3 MeV (93%) →7Li + α + 2,79 MeV (7%)n+157Gd → Gd* → γ-ray → conv. electron up to 182 KeVn+235U → fission fragmentsn+239Pu → fission fragments
0,001 0,01 0,1 1
102
103
104
105
106
3He
10B
6Li
natGd
Energy (eV)C
ross
-sec
tion
(bar
n)
From P.Convert, J.Bruce Forsyth “Position sensitive detectors of thermal neutrons”
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Scintillation PSDs
Scintillator
n
CCDcamera
Electronics
Reflector
PM1 PM2
Decoder
Discretescintillationelements
n
Optic fibres
Photomultipliers
Discrete elements PSD
Scintillator with CCD-camera
Photomultipliers
nReflector
PM1 PM2 PM3
Scintillator
Lightdisperser
The Anger cameraFrom P.Convert, J.Bruce Forsyth “Position sensitive detectors of thermal neutrons”
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Gaseous PSD
e
From F. Sauli “Survey of the GEM technology and applications”
e
Microstrip detectors GEM-based detectors
Multi-wire proportional chambersArray of counters
e
+Hv+Hv
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Types of PSD
Spatial resolution
Efficiency Linearity StabilityCount Rate
γ-sensitivity Note
Counter Array 5 mm 90% Good* Excelent High Very Low
MWPC 1 mm 80% 5% Good High* Very Low
Microstrip 1 мм 80% No data Good Good Very Low
Small active area
GEM-based 0,1 мм 80%* Good Good Low
Discrete element scintillator 3 mm 90% 3%
Quiet good Good High
The Anger camera 3 mm 85% 7%
Quiet good Good High
Scint. with CCD-camera 0,5 мм 60% 3% No data
No data High
Films 0,05 мм * 7% GoodNo data Low
Not suited for TOF
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Developments of FLNP JINR 2D monitor for thermal neutrons
Active area 100x100 mm2
Spatial resolution 4x4 mm2
Direct beam weakening <5% Intended for direct beam observation
1D multi-purpose PSD Active area 200x800 mm2
Spatial resolution 1,8 mm Multi-purpose detector for neutron
diffraction and reflectometry 2D multi-purpose PSD
Active area 225x225 mm2
Spatial resolution 2x2 mm2
Multi-purpose detector for various neutron scattering measurements
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Experimental results
Diffraction spectraDiffraction spectra of theof the (La(La0.10.1PrPr0.90.9))0.70.7CaCa0.30.3MnMn0.30.3 sample, measured at the sample, measured at the
channel channel №5№5. of the IBR-2 reactor. . of the IBR-2 reactor.
T=10T=10˚K˚KT=290T=290˚K˚K
Profile of the channelProfile of the channel №10 №10 of the IBR-2 of the IBR-2 Profile of the channel Profile of the channel №6№6b of the IBR-2b of the IBR-2
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Results A great progress in development of PSD`s
for detection of thermal neutrons have been achieved. But on the present moment there is no type of detectors, that completely satisfied all demands of the physicists.
Leading world centers of neutron research continues work for further improvements of their detector complexes.
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics
Thank your for attention!
IX International school-seminar: Actual problems of microworld physicsIX International school-seminar: Actual problems of microworld physics