Study of Position Sensitive E-E for Space Particle Telescope

Pre-results of Geant4 simulation

张云龙，王文骁，李翠

Motivation

• Study of space science is in need of information of space particle(nuclide/ion).

• Important parameters: energy spectrum of particle and particle flux.

• First of all, identify particles. (Reconstruct Z and M in simulation.)

Particle identification

22ln

211 2

2max

222

22

ITcm

AZkz

dxdE e

Bethe-Bloch formula:

Energy loss of incident particle could be described by Bethe-Bloch formula.

• Due to ionization , particle will deposit energy in detector, and detector can output signal.

• The value of output signal in detector relevant to the incident particle’s charge, kinetic energy and so on.

• With measured detector’s signal, the particle’s charge and mass could be identified.

Telescope model

Elements’ thickness:First: 50mSecond: 192mThird: 248mBGO: 63mm63mm40mm

BGO

Silic

on d

etec

tor

z

xy

0.0

6080

90

H1H2H3• /gps/source/clear

• /gps/source/add 1• /gps/particle proton• /gps/pos/type Point• /gps/pos/centre 0. 0. 9.1 cm• /gps/ang/type iso• /gps/ang/mintheta 0.00 deg• /gps/ang/maxtheta 15.00 deg • /gps/ene/type Lin• /gps/ene/min 0. MeV • /gps/ene/max 200. MeV • /gps/ene/gradient 0.• /gps/ene/intercept 1.

• /run/beamOn 20000

/gps/source/clear/gps/source/add 1/gps/particle ion/gps/ion 1 3 1 0 /gps/pos/type Point/gps/pos/centre 0. 0. 9.1 cm/gps/ang/type iso/gps/ang/mintheta 0.00 deg/gps/ang/maxtheta 15.00 deg/gps/ene/type Lin/gps/ene/min 0. MeV/gps/ene/max 200. MeV/gps/ene/gradient 0./gps/ene/intercept 1.

/run/beamOn 20000

/gps/source/clear

/gps/source/add 1/gps/particle ion/gps/ion 1 2 1 0 /gps/pos/type Point/gps/pos/centre 0. 0. 9.1 cm/gps/ang/type iso/gps/ang/mintheta 0.00 deg/gps/ang/maxtheta 15.00 deg/gps/ene/type Lin/gps/ene/min 0. MeV/gps/ene/max 200. MeV/gps/ene/gradient 0./gps/ene/intercept 1.

/run/beamOn 20000

Energy deposit in each Si Layer and BGO

H1

Energy deposit in each Si Layer and BGO

H2

Energy deposit in each Si Layer and BGO

H3

E VS Kinetic energy

He3He4• /gps/source/clear• /gps/source/add 1• /gps/particle alpha• #/gps/ion 2 4 2 0 • /gps/pos/type Point• /gps/pos/centre 0. 0. 9.1 cm• /gps/ang/type iso• /gps/ang/mintheta 0.00 deg• /gps/ang/maxtheta 15.00 deg• /gps/ene/type Lin• /gps/ene/min 0. MeV• /gps/ene/max 400. MeV• /gps/ene/gradient 0.• /gps/ene/intercept 1.

• /run/beamOn 20000

/gps/source/clear

/gps/source/add 1/gps/particle ion/gps/ion 2 3 2 0 /gps/pos/type Point/gps/pos/centre 0. 0. 9.1 cm/gps/ang/type iso/gps/ang/mintheta 0.00 deg/gps/ang/maxtheta 15.00 deg/gps/ene/type Lin/gps/ene/min 0. MeV/gps/ene/max 400. MeV/gps/ene/gradient 0./gps/ene/intercept 1.

/run/beamOn 20000

Energy deposit in each Si Layer and BGO

He3

Energy deposit in each Si Layer and BGO

He4

E VS Kinetic energy

Li6Li7• /gps/source/clear

• /gps/source/add 1• /gps/particle ion• /gps/ion 3 6 3 0• /gps/pos/type Point• /gps/pos/centre 0. 0. 9.1 cm• /gps/ang/type iso• /gps/ang/mintheta 0.00 deg• /gps/ang/maxtheta 0.01 deg • /gps/ene/type Lin• /gps/ene/min 0. MeV • /gps/ene/max 400. MeV • /gps/ene/gradient 0.• /gps/ene/intercept 1.

• /run/beamOn 10000

/gps/source/clear

/gps/source/add 1/gps/particle ion/gps/ion 3 7 3 0 /gps/pos/type Point/gps/pos/centre 0. 0. 9.1 cm/gps/ang/type iso/gps/ang/mintheta 0.00 deg/gps/ang/maxtheta 0.01 deg/gps/ene/type Lin/gps/ene/min 0. MeV/gps/ene/max 500. MeV/gps/ene/gradient 0./gps/ene/intercept 1.

/run/beamOn 10000

Energy deposit in each Si Layer and BGO

Li6

Energy deposit in each Si Layer and BGO

Li7

E VS Kinetic energy

Be7Be9Be10

B10B11

C12C13C14

Reconstruct ZNUCLEAR INSTRUMENTS AND METHODS 145(1977) 583-591

The final calculated particle identification value “PI” , approximately (AZ2)1/3

PI calculation

T1: thickness of E detectorE1: EE2: total energy

Reconstruct Z

H1

H2 H3

He3

He4

Li6

Li7Be

BC

Reconstruct M

• Once the charge (Z) has been identified, the mass M of the specific isotope can be reconstructed by means of the equation:

• A precise evaluation of such parameters a and b for each atomic species has been obtained by a fit of the following expression:

R: the measured rangeE: kinetic energya: is a constant of the mediumb: [1.5, 1.8]

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH A 424(1999)414-424

Measured range VS Kinetic energy

proton alpha

Li Be

Measured range VS Kinetic energy

B C

Values of a&b

Z 1 2 3 4 5 6

a 0.54379 0.547179

0.548704 0.544568 0.54164 0.538426

b 1.76860 1.77122 1.77243 1.76954 1.7673 1.76466

mass

H1 H2H3

He3 He

4

mass

Li6 Li7 Be7

Be9 Be10

B10 B1

1

C12

C13 C1

4