[PPT] - ' $ Multiple Sattering in GEANT4, latest dev elopmen ts 1 PowerPoint Presentation

SLIDE 1 Multiple S attering in GEANT4, latest dev elopmen ts 1 ' & $ % Multiple S attering in GEANT4, latest dev elopmen ts L

aszl
Urb
an,

Cen tral Res.Inst.Ph ys., Budap est 1 O t 2002 Abstra t hanges in the MSC mo del in G4, tests/v alidation i.e. G4/data

mparisons

+ some G3 results G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 2 Multiple S attering in GEANT4, latest dev elopmen ts 2 ' & $ % Change in MSC sin e Gean t4 V4.1 Mo died angle distribution fun tion : g (u) = q [pg 1 (u) + (1

p)g

2 (u)℄ + (1

q

)g 3 (u) (1) where u =

s

g 1 (u) = 1 exp [a(1

u)℄

for u 2 [u ; 1℄ g 2 (u) = 2 [(b

u)
℄

for u 2 [1; u ℄ g 3 (u) = 3 i are normalization

nstan

ts, a; b; ; u and the w eigths p; q are mo del parameters. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 3 Multiple S attering in GEANT4, latest dev elopmen ts 3 ' & $ % Where this fun tional form

mes

from?

g

1 (u) is Gaussian for small

,

g 1 (u) = exp [ a 2 2 ℄

g

2 (u) has a Rutherford-lik e tail for b

1

and

2
g

3 =

nstan

t for simpli it y (the rst t w

me

from the ph ysi s) G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 4 Multiple S attering in GEANT4, latest dev elopmen ts 4 ' & $ % Determination

f

the parameters All

f

them are fun tions

f

the v ariable

=

=t, where

is

the transp

rt

mean free path, t is the (true) path length. Requiremen ts for g (u): 1. g (u) and the 1st deriv ativ e should b e

n

tin uous at u = u 2. theoreti al mean v alue

f

u =

s

should b e repro du ed b y g (u) 3. angle distribution

f

15.7 MeV e- after thin Au foils should b e repro du ed (t) 4.

2

=< u 2 >

<

u > 2 should b e appro ximately agree with theory G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 5 Multiple S attering in GEANT4, latest dev elopmen ts 5 ' & $ % The (simple) fun tional form

f

the mo del parameters an b e found in the

de,

there are altogether 5

nstan

ts, whi h determine the mo del

mpletely

.

This

new v ersion agrees b etter with the exp erimen tal data than the results

f

v ersion 4.1 (and than the results

f

GEANT3 in some ases).

This

new v ersion giv es a w eak er step/ ut dep enden e than the v ersion 4.1 F

llo

w some tests whi h sho w the qualit y

f

the results. Most

f

them are G4 sim ulation

mpared

to exp. data, but in some ases GEANT3 results are sho wn as w ell. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 6 Multiple S attering in GEANT4, latest dev elopmen ts 6 ' & $ % Angle distributions, Gean t4 V4.1 with new MSC

Angular distribution of 15.7 MeV e- after Au foils

10

7

10

6

10

5

10

4

10

3

10

2

10

1

5 10 15 20 25 30

G4 (18.66 mg/cm2) G4 (37.28 mg/cm2)

angle(deg)

= ) G4 = data from Ref. 1. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 7 Multiple S attering in GEANT4, latest dev elopmen ts 7 ' & $ % Angle distributions, GEANT3 (MSC Moliere)

Angular distribution of 15.7 MeV e- after Au foils

10

7

10

6

10

5

10

4

10

3

10

2

10

1

5 10 15 20 25 30

G3 (18.66 mg/cm2) G3 (37.28 mg/cm2)

angle(deg)

= ) G3

data,

agreemen t sligh tly b etter for G4 G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 8 Multiple S attering in GEANT4, latest dev elopmen ts 8 ' & $ % Depth-dose distribution

f

500 k eV e- in Al

Energy deposit of 0.5 MeV e- in Al as a function of depth 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

G4 4.1+new MSC

t/r0

r

range
f

the 500 k eV e- in Al, data tak en from Ref. 2. = ) G4 = data within errors (G3 giv es shorter distribution) G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 9 Multiple S attering in GEANT4, latest dev elopmen ts 9 ' & $ % T ransmission

f

25 k eV e- through Al foils

transmission coeff. of 25 keV e- (Al) 20 40 60 80 100 200 400 600 800 1000 1200 1400

t(microg/cm2) %

lowenergy MC of Ref. 4 G4 4.1 + new MSC data from Ref. 3

= ) G4 = l.e. MC

f

Ref. 4

data

from Ref. 3. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 10 Multiple S attering in GEANT4, latest dev elopmen ts 10 ' & $ % T ransmission

f

1 MeV e- through Al la y ers

transmission coeff. of 1 MeV e- (Al) 20 40 60 80 100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

t/r0 ctran %

GEANT3 G4 4.1+new MSC,fr 1.0 G4 4.1+new MSC,fr 0.01 data taken from Ref.3

= ) G4 results loser to data than G3 results, fr = 0.01

data

, fr = 1 (no b

undary

algorithm) sligthly small

es

but transmission is not to

sensitiv

e to the v alue

f

fr. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 11 Multiple S attering in GEANT4, latest dev elopmen ts 11 ' & $ % Ba ks attering

f

e-/e+ small uts (1 k eV) b

th

in G4 and G3 GEANT4 sim ulation is lose to data, GEANT3 6= data .... GEANT4

step

limitation when en tering a v

lume

+ go

d

MSC angle distribution GEANT3

far

from data ev en in the ase

f

using step limit = ) angle distribution is not go

d

enough ... G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 12 Multiple S attering in GEANT4, latest dev elopmen ts 12 ' & $ % Ba ks attering

f

e- from Au, energy dep enden e

backscattering coeff. of e- (Gold) 10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70

kin. energy(keV)

%

GEANT3 def GEANT3 stmx=1 mic G4 4.1+new MSC,fr def G4 4.1+new MSC,fr 0.01 data from Ref. 3

= ) G4 results loser to data than G3 results, fr = 0.01

data

ba ks attering

e.

is sensitiv e to the v alue

f

fr. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 13 Multiple S attering in GEANT4, latest dev elopmen ts 13 ' & $ % Ba ks attering

f

40 k eV e- from C, angle dep enden e

backscattering coeff. of 40 keV e- (C) 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 90

angle of incidence(deg) %

GEANT3 def GEANT3 stmx=0.01 range G4 4.1+new MSC,fr def G4 4.1+new MSC,fr 0.01 data from Ref. 3

= ) G4 results loser to data than G3 results, fr = 0.01

data

ba ks attering

e.

is sensitiv e to the v alue

f

fr. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 14 Multiple S attering in GEANT4, latest dev elopmen ts 14 ' & $ % Ba ks attering

f

35 k eV e+ from Au, angle dep enden e

backscattering coeff. of 35 keV e+ (Au) 10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90

angle of incidence(deg) %

GEANT3 stmx=0.01 range G4 4.1+new MSC,fr 0.01 data from Ref. 5

= ) G4 with fr = 0.01

data,

G3 giv es zero ba ks attering for e+, probable reason: annihilation ross se tion is to

big

at lo w energy in GEANT3. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 15 Multiple S attering in GEANT4, latest dev elopmen ts 15 ' & $ % Ba ks attering

f

60 k eV e- from di. materials, Z dep enden e

backscattering coeff. of 60 keV e- for diff. materials 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 90 100

atomic number (Z) %

GEANT3 def GEANT3 stmx=0.01 range G4 4.1+new MSC,fr def G4 4.1+new MSC,fr 0.01 data of Ref. 3

= ) G4 with f r = 0:01

data,

G3 results far from data. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 16 Multiple S attering in GEANT4, latest dev elopmen ts 16 ' & $ % Ba ks attering

f

1 MeV e- from di. materials

Energy and angle distribution of backscattered electrons (T0=1 MeV) 250 500 750 1000 1250 1500 1750 2000 2250 2500 0.25 0.5 0.75 1

Al Fe Sn Au

MeV

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 100 120 140 160 180

Al Fe Sn Au

deg

G4 sim ulation , 0.001 mm uts. Ni e agreemen t with data

f

Rester and Derri kson(ref.6, not sho wn here) G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 17 Multiple S attering in GEANT4, latest dev elopmen ts 17 ' & $ % Step dep enden e

f

MSC in G4 4.1 and G4 with new MSC

Step dependence of MSC, angle distr. of 2 MeV e- after 1 mm Si 0.2 0.4 0.6 0.8 1 1.2 20 40 60 80

10 steps 5 steps 2 steps

deg

0.2 0.4 0.6 0.8 1 1.2 20 40 60 80

10 steps 5 steps 2 steps

deg

= ) step dep enden e is w eak er with new MSC G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 18 Multiple S attering in GEANT4, latest dev elopmen ts 18 ' & $ % Step dep enden e

f

MSC in GEANT3 and GEANT4

Step dependence of MSC, angle distr. of 2 MeV e- after 1 mm Si 50 100 150 200 250 300 350 400 450 500 20 40 60 80

100 steps 2 steps 1 step

deg

1 2 3 4 5 20 40 60 80

100 steps 2 steps 1 step

deg

= ) step dep enden e is sligthly w eak er in G4 and the tails are dieren t (normalization dieren t in G3/G4) G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002

SLIDE 19 Multiple S attering in GEANT4, latest dev elopmen ts 19 ' & $ % Referen es: 1. A.O.Hanson et al. Ph ys.Rev.84(1951)634. 2. S.M.Seltzer,M.J.Berger NIM 119(1974) 157. 3. G.Neub ert,S.Rogas hewski J.Ph ys.D Appl.Ph ys. 17(1984)2439. 4. J.M. F ern andez-V area et al. NIM B108(1996) 35. 5. P .G.Coleman et al. J.Ph ys. Condens.Matter 4(1992) 10311. 6. D.H.Rester and J.H.Derri kson NIM 86(1970) 261. G4 W

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CERN L.Urb an(CRIP ,Budap est) 1 O t 2002