Compton Camera development for the imaging of high energy gamma rays 1 Martin Jones UNTF 2010...

Compton Camera development for the imaging of high energy gamma rays

1

Martin Jones

UNTF 2010 Salford – April 14th 2010

Email: [email protected]

Martin Jones – UNTF April 2010

Overview

2

•Introduction to the Distinguish Project

•Compton Imaging

• Detectors

•Current work

•Summary


The Distinguish project

3

• Developing a highly specific detection and imaging system for the detection and quantification of narcotics and more notably, explosives.

• Current imaging systems are based on methods such as conventional X-ray imaging through to CT scanners which provide the user with a high level of shape and density information of objects contained within luggage/cargo.

• This method does not provide any nuclide identification .• Industry has indicated a desire to deduce the composition of suspect objects using current novel imaging techniques.


The Distinguish project

4

• Explosives/narcotics contain combinations of the lighter elements

•Elements such as Oxygen, Carbon and Nitrogen which have characteristic gamma rays

• After neutron interrogation these characteristic gamma rays will be emitted

An illustration of the chemical difference between Dynamite (a) and TNT (b)

(a) (b)


•Oxygen - 6.13MeV, Nitrogen - 5.11MeV, 2.31MeV, 1.64MeV, Carbon – 4.43MeV

Compton Imaging

5

E1

E2

E1

E2

Projected Cones

Location of point source

01

2 111

EEcmCos o

0E

•The Compton imaging technique is to be

used to localise the source of gamma

rays

•Cone reconstruction method defines that the

area of maximum overlap is attributed to

source location

• Scatter detector – good energy resolution,

position dependence

•Absorber detector - high stopping power and

position dependence

• Looking at energies in the range of 0.5-

5.0MeV

210 EEE


Gamma-ray detection and imaging

6

The scatter detector • Planar HPGe detector

• 60 x 60 x 20mm active volume

•12 x 12, 5mm wide orthogonal strips

• position resolution – in order of a cubic mm

• Energy resolution (1.53keV @ 122keV)


Gamma-ray detection and imaging

7

The absorber detector • 64 pixel CsI detector (8 x 8)

•Photomultiplier – 64 pixels (8 x 8)

• 64 individual preamps

• High stopping power

• 51.6 x 51.6 x 50mm active volume with 4.48 x 4.48 x 50mm pixels


Geant4 validation

8 Martin Jones – UNTF April 2010

L.J. Harkness, et al., Nucl. Instr. and Meth. A (2009)

Current progress – Simulations

9

• Germanium - Germanium configuration

• 5cm source – detector and detector – detector separation

• Germanium - Caesium Iodide configuration (5cm, 2cm and 10cm CsI simulations)

• 5cm source – detector and detector – detector separation


Simulations


Klein-Nishina


Simulated detector ‘maps’


The next step

17

1. Generate images using current Compton reconstruction code that has been developed in Liverpool.

2. Assess image quality. (Efficiency and image resolution).

3. Add in other factors to the simulations such as energy resolution and position resolution.

4. Implement all of the above experimentally.


The next step.

18

• Full detector characterisation to be complete. Detector is on scanning table

• Will be performed using X-Y scanning table.

• Move in increments of 1mm.

• Collimated beam of 122keV gamma-rays. (Co-57).

• Quantify the uniformity of each pixel.


The next step.


Summary.

20

•Energies of interest 0.5-5.0MeV.

• Geometry decided based on simulated efficiency.

• Initial simulated images. - Image quality/position resolution.

• Raster scan of CsI detector using Co57

• Aim to complete imaging with Ge/Ge and Ge/CsI in Compton camera mode.


M.P.Jones1 , A.J. Boston1, H.C Boston1, R.J. Cooper 1 M.R. Dimmock1,

L.P. Gaffney1, A.N. Grint1, L.J. Harkness1, D. Judson1, P.J. Nolan1, D.C. Oxley1,

B. Pietras1, A. Sweeney1, M.J. Joyce2, R.O. Mackin2, M.D. Aspinall2, A.J. Peyton3,

R.G. Silfhout3

1 Department of Physics, University of Liverpool, UK

2 Department of Engineering, Lancaster University, UK

3 School of Electronic and Electrical Engineering, The University of Manchester,

UK


Compton Camera development for the imaging of high energy gamma rays 1 Martin Jones UNTF 2010...

Documents

Transcript of Compton Camera development for the imaging of high energy gamma rays 1 Martin Jones UNTF 2010...