DETERMINATION OF DETERMINATION OF ELEMENTAL COMPOSITIONS ELEMENTAL COMPOSITIONS

BY USING NEUTRON BY USING NEUTRON RESONANCE SPECTROSCOPICRESONANCE SPECTROSCOPIC

MAHMOUD GAAFARMAHMOUD GAAFAR

TEACHING ASSISTANT, PHYSICSFACULTY OF SCIENCE, MENOUFIA UNIVERSITY

OUTLINOUTLINEE

ECR ION ECR ION SOURCESSOURCES

INTENSE RESONANCE NEUTRON SOURCE INTENSE RESONANCE NEUTRON SOURCE (IREN)(IREN)

• NEUTRON RESONANCE CAPTURE NEUTRON RESONANCE CAPTURE ANALYSISANALYSIS

• EXAMPLE -> CU-ZN ALLOYEXAMPLE -> CU-ZN ALLOY

ECR Ion Source

4Ion sourceIon source

Axial injection systemECR ion source

5

The ECR ion source

ωECR

~ B×e /me

2])[(101024.124

2GHzf

e

mec

n

6

DECRIS-2 – U-400M cyclotron – 1995

ECR-4M – U-400 cyclotron – 1996 (collaboration FLNR – GANIL (France))

DECRIS-3 – TESLA Accelerator Installation (Belgrade) -1997

DECRIS-2m – BIONT Inc. (Bratislava) – 2003

DECRIS-SC – CI-100 cyclotron - 2004

DECRIS-3 - DC-60 accelerator complex (Astana, Kazakhstan) – 2006

DECRIS-4 – in operation at the test bench - 2006

DECRIS-2m – tested DC-72 cyclotron (Bratislava)

DECRIS-SC2 – new ion source for U-400M – under commissioning

DECRIS-SC3 – for DC-350 cyclotron - project

DECRIS - Dubna ECR Ion Sources

DECRIS-2, DECRIS-2m, DECRIS-3, DECRIS-4 are “room temperature” ECR ion sources. The axial magnetic field is created by two coils with independent power supplies. The radial magnetic field is created by permanent magnet hexapole, made from NdFeB.

DECRIS-SC – axial magnetic field is created by superconducting solenoids

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FLNR (JINR) CYCLOTRONS WITH ECR ION SOURCES

FLNR (JINR) CYCLOTRONS WITH ECR ION SOURCES

NEW CYCLOTRONSNEW CYCLOTRONS NEW CYCLOTRONSNEW CYCLOTRONS

CI-100 + DECRIS-SCU400 + ECR4M U400M + DECRIS-2

DC-72

DECRIS-2m

DC-60

DECRIS-3

INTENSE RESONANCE NEUTRON SOURCE (IREN)

Pulsed Source for Applied and fundamental Investigations

The IREN source of three basic parts:

1) Vertically electron linear accelerator (linac) LUE-200.

2) Vacuum pipeline for transportation of the electron beam to the electron-neutron converter.

3) Electron – neutron converter located in the center of material absorbes charged radiation (blanket).

The IREN Source

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MAIN PARAMETERS OF THE LINAC LUE-200

Max. Electron Energy 75 MeV

Av. electron energy 30 MeV

Pulse current 2.8 A

Pulse width 100 ns

Repetition rate 50 Hz

Beam power ~1kW

Neutron intensity ~1012 n/s

Neutron Resonance Capture Analysis

used to determine the elementalcomposition of materials and artifacts

Interaction of neutrons with nuclei as a function of neutron energy shows sharp peaks, known as resonances, at energies specific for each isotope .

Resonances are thus the fingerprints of elements. They can be visualized in the neutron capture spectrum

as a function of neutron energy.

The energy of a neutron can be determined by measuring the time of flight ( the time it needs to travel a known distance L in m).

With a pulsed neutron source the time-of-flight (T in µs) can be determined from the start pulse of the source and a stop pulse generated by detection of the prompt capture gamma rays.

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TIME OF FLIGHT NEUTRON SPECTROSCOPY

Detector

Flight path L, mSource

Collimator

Sample

dt

EXPERIMENTAL FACILITY

1.Photo multiplier , 2. Sample, 3. scintillator section Large volume liquid scintillator detector consisting of 6 sections 20 liters each was placed at 60 meters flight path. Sample installed inside the detector.

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The energy of a neutron can be determined by

2

310227.5

st

mLeVEn

232108.2 nn E

mL

sdteVE

2222

L

dL

t

dt

E

E

n

n

Time of flight Energy channel .no (TDC)

0 200 400 600 800 1000 12000

20

40

60

80

100

120

140

160

180

200

220

240

cou

nts

channel

Before Calculation

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RAW EXPERIMENTAL DATA

THE CALIBRATION LINE

ACKNOWLEDGEMACKNOWLEDGEMENTENT

SPECIAL THANKS TO PROF. PAVEL SPECIAL THANKS TO PROF. PAVEL SEDYSHEV (FLNP)SEDYSHEV (FLNP)

THANKS TO THANKS TO JINRJINR

THANKS TO ASRT - THANKS TO ASRT - EGYPTEGYPT

SPECIAL THANKS TO PROF. BORIS SPECIAL THANKS TO PROF. BORIS (FLNR)(FLNR)

THANKS THANKS