geant4 simulations for the r3b calorimeter · geant4 simulations for the r3b calorimeter ajé m i...

GEANT4 SIMULATIONS GEANT4 SIMULATIONS FOR THE FOR THE

R3B CALORIMETERR3B CALORIMETERR3B CALORIMETERR3B CALORIMETER

J é A i B i M M C G ll d dJosé Antonio Briz Monago, M. Carmona-Gallardo and

M.J.G. Borge, A. Perea, O. Tengblad, M. TurriónJ g g

O liO liMAGISOL meeting Madrid, January 19th 2009

OutlineOutline

Introduction: FAIR at GSI (Germany)

R3B Experiment

Calorimeter: Structure

Requirements

Forward endcap: Phoswich?

Experimental tests

Ongoing work:

Experimental tests

Geant4 Simulations

First crystal length

How long must be 2nd crystal?

Energy transfer to neighboring crystals

Summary and Future work

Total Crystal’sVolume calculations

Energy transfer to neighboring crystals

Summary and Future work

2Geant 4 Simulations for the R3B Calorimeter José A. Briz

FAIRFAIRMAGISOL meeting Madrid, January 19th 2009

FAIRFAIR((FFacilityacility forfor AAntiprotonntiproton and and IIon on RResearchesearch))

GSI today

Future facility

New accelerator complex at GSI (Darmstadt, Germany) in 2012

Beams of stable and radiactivenuclei and antiprotons

Higher beam intensities: 1012Higher beam intensities: 10ions/s at 2-30 GeV/u

NUSTAR(Nuclear STructure, Astrophysics and Reactions)

R3B experiment


33

MAGISOL meeting Madrid, January 19th 2009

RR33B B ExperimentExperiment((RReactionseactions withwith RRelativisticelativistic RRadiactiveadiactive BBeamseams))

Studies of reactions in inverse full kinematics

Reactions to be considered in R3B experiment:

• Elastic and quasi-elastic scattering

• Coulomb excitation

• Knockout reactions

• Total-absorption and charge-exchange reactions

• Fission and spallation

• Fragmentation and multifragmentation

4

Calorimeter: CALIFA

Geant 4 Simulations for the R3B Calorimeter José A. Briz

C ’ C ’


CALIFA’s CALIFA’s RequirementsRequirements((CALCALimeterimeter for for IInn--FFlight light gammgammAA detection)detection)

PROPERTIES REQUIRED VALUES

Total absorption efficiency 80 % (up to Eγ= 15 MeV Lab system)

γ sum energy <10%( )

⟩⟨ sum

sum

EEσ

( )Nσγmultiplicity <10%

Good γ energy resolution 3-5 %

Calorimeter for high energy light charged particles Up to 300 MeV in Lab system

( )⟩⟨ γ

γ

NNσ

⎟⎠⎞

⎜⎝⎛

EΔE

Calorimeter for high energy light charged particles Up to 300 MeV in Lab system

Good light charged particle energy resolution < 3 % ⎟⎟⎠

⎞⎜⎜⎝

⎛

p

p

EΔE

Prime mission: measure γ (50 keV 25 MeV) with optimal energy resolution (ideally < 5%)

R3B Calorimeter Collaboration: USC (Spain), LUND (Sweden), IEM (Spain), GSI (Germany), Chalmers (Sweden),

Prime mission: measure γ (50 keV – 25 MeV) with optimal energy resolution (ideally < 5%)

5

USC (Spain), LUND (Sweden), IEM (Spain), GSI (Germany), Chalmers (Sweden), Daresbury (UK), Univ. Complutense (Spain), KTH Stockholm (Sweden), IPN Orsay (France), JINR (Russia), TUD (Germany), TUM (Germany)



Based on angular distribution of emitted γ rays and its corresponding Doppler shift

CALIFA’sCALIFA’s StructureStructureBased on angular distribution of emitted γ rays and its corresponding Doppler shift(because of γ rays sources are moving with relativistic energies).

◦ Barrel: Region from ~40º up to 130º in polar angles

F d d F 7º t 40º◦ Forward endcap: From ~ 7º up to ~40º



Forward Forward endcapendcap: : PhoswichPhoswich??

Contribute to design of CALIFA's forward endcap. In principle, we’ll record:◦ γ-rays in the energy region 50 keV - 25MeV (~50% of total γ-rays emitted by a moving source)

◦ Protons up to 300 MeV in Lab system

Our suggestion: two new generation scintillators crystals layers in a phoswichconfiguration with only one common readout (crystals must be optically compatibles).

◦ For protons: useful for particle telescope ∆E/E identification: solve ambiguity

Deposited energy by a charged particle in a material according to Bethe-Bloch equation

◦ For gammas: energy and efficiency optimization at reduced costg gy y p



Experimental Experimental teststestsPh i h L B (3 ) + L Cl (5 )Phoswich: LaBr3 (3 cm) + LaCl3 (5 cm)

Material Energy Resolution(at 662 keV) (%)

Light yield(photons/keV γ)

Decay time (ns)

LaBr3 2.9 63 16

ST. GOBAIN PHOSWICH HAMAMATSU R5380 PMT

LaCl3 3.8 49 28

ENERGY SPECTRUM WITH GATE A

PHOSWICH ENERGY SPECTRUM FWHM 6.27% at 662 keV

TEMPORAL SPECTRUM

ENERGY SPECTRUM WITH GATE B

FWHM 4 41%

8

FWHM 4.41% at 662 keV



CrystalsCrystals optimizationoptimization: : simulationssimulations

Geant4 simulations purposes◦ Comparison with experimental tests in our Lab

◦ Search for the best material and size of each crystal (following CALIFA’srequirements)

◦ Analysis of energy transfer to the neighboring crystals: very important forelectronic components (coincidences and summing)

First configuration analyzed is: First configuration analyzed is:

• LaBr3 in a 3x3 array.

• 20x20 mm2 frontal surface of each crystal

• Total energy deposited (9 crystals)Total energy deposited (9 crystals)

• Gamma-rays from 500 keV up to 30 MeV

• Incidence on central crystal

• Distance source-detector = 20 cm

9

Distance source detector 20 cm



FirstFirst crystalcrystal lengthlengthStudying first interaction depth for LaBr3: we need to make sure that gamma particles interact in first crystal

First hit depth

80

90

100

e(%

)

50

60

70

ticl

epe

rcen

tag

0,5 MeV

1 MeV

2 MeV

30

40

Inci

dent

part 5 MeV

10 MeV

20 MeV

30 M V

10

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Depth (cm)

30 MeV

10

With 7 cm length we get 70% (at least) incidentparticles have been detected. Probably is a goodelection for first crystal length



HowHow longlong mustmust bebe 22ndnd crystalcrystal??

100

Photopeak efficiency (90%) with respect to crystal length

• Studying Photopeak efficiency

70

80

90

100

)

30

40

50

60

Effi

cien

cy (

%)

0.5 MeV1 MeV

0

10

20

3

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

2 MeV5 MeV10 MeV20 MeV30 MeV

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Depth (cm)

From 15 cm of LaBr3 practically efficiency don´ti hi b l h i h l h

11

improve: a hint about total phoswich length


EE t f t f MAGISOL meeting Madrid, January 19th 2009

EnergyEnergy transfer transfer toto neighboringneighboring cristalscristals

◦ Photopeak efficiency (90% initial energy deposited)

80

90

100

%)

3x3 Array LaBr3

80

90

100

%)

5x5 Array LaBr3

30

40

50

60

70

opea

kE

ffici

ency

(%

40

50

60

70

opea

kE

ffici

ency

(%

0

10

20

30

0 2 4 6 8 10 12 14 16 18 20

Pho

t

0.5 MeV 1 MeV2 MeV 5 MeV10 MeV 20 MeV30 MeV

0

10

20

30

0 2 4 6 8 10 12 14 16 18 20

Pho

to

0.5 MeV 1 MeV2 MeV 5 MeV10 MeV 20 MeV30 MeV

◦ Better photopeak efficiencies for 5x5 array (about 5 % for 7 cm length)

◦ Next tests: compare results for 5x5 with 7x7

0 2 4 6 8 10 12 14 16 18 20

Depth (cm)

0 2 4 6 8 10 12 14 16 18 20

Depth (cm)

◦ Next tests: compare results for 5x5 with 7x7


Total Total Crystal’sCrystal’sVolumeVolumeMAGISOL meeting Madrid, January 19th 2009

Total Total Crystal sCrystal sVolumeVolumeTotal Crystal’sVolume: Variation with respect to inner radius analysisAt present, inner radius in barrel is stablished to be 300 mm

Total volume’s variation with respect to inner radius

8090

100110

lum

erd

end

cap

)m

e fo

r r i=

300m

m)

inner radius

3040506070

Tot

al v

ol(b

arre

l + fo

rwar

wit

h re

spec

t to

vol

um

300mm

200mm

01020

50 100 150 200 250 300 350

( %

Reduction of number of crystals as well as # of readout channels

If we reduce inner radius to 200 mm, volume of detector material used isb t 50 % ( ith th t l l th)

inner radius (mm)

about 50 % (with the same crystal length)



SummarySummaryNecessary to sum more neighboring crystals

(as shown 5x5 better efficiency than 3x3)Phoswich dimensions: two crystals 7 + 8 [cm] or one crystal 15 cmy [ ] yTransmit to the rest of collaboration:

small reduction of inner radius = big reduction of cost(# crystals as well as # readout channels)(# y # )

FutureFuture workworkPerform simulations with protonsIntroduce real dimensions of crystalsIntroduce real dimensions of crystalsImplementation of LITRANI code for creation and propagation of scintillation photons to obtain realistic spectra with energy resolution of crystalscrystals


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