GAMMA-PARTICLE ARRAY FOR DIRECT REACTION STUDIES SIMULATIONS
Jan 20, 2016
GAMMA-PARTICLE ARRAY FOR DIRECT REACTION STUDIES
SIMULATIONS
Detection challenges for (d,p) reactions 78Ni(d,p)79Ni @ 10 MeV/u
A
Challenges:
Kinematics compression ->Ep good resolution
States separated by 1 MeV ->~200 keV in Ep
Covers large range in θ_lab(deg) ->4pi ang cover
Deposit of low Energy->Threshold problems
Doppler Broadening
Measurements->Observables
Ep and/or E ->Ex
θp -> dσ/d -> (l , SF)
θ_lab(deg)
En
erg
y (M
eV)
PHYSICS CASE : DIRECT REACTION STUDIES
Key experiments: Mapping of single-particle energies using transfer reactions
• 78Ni(d,p)79Ni @ 10 MeV/u
• 132Sn(d,p)133Sn @ 10 MeV/u
Reactions :
• Elastic and inelastic scattering
• Transfer reactions
ASUB-TASK: SINGLE-PARTICLES and COLLECTIVE PROPERTIES
Integrated particle and gamma detection system : Direct reactions studies
132Sn(d,p)133Sn @ 10 AMeV
Particle array (Simulations)
PARTICLE ARRAY: Simple Geometry
Distance to (0,0,0) = 5 cm
Box of 4 Silicon detectors :
Area =10*10 cm2
Detector Thickness =300um
Source of protons with kinematics from reaction placed at (0,0,0)
No target
X
Z
YINPUT:
Energy Resolution
Strip pitch size
Thickness detector (punch through)
Target thickness effect
STUDY of the θ and Ex
PARTICLE ARRAY: Angular Resolution
If Strip pitch ~ 1mm ->number of channels for 10 cm detector 100*100=10000
6 detectors =6x10000 channels (pad-type detector)
6 detectors =6x(100+100) channels (strip-type)
PARTICLE ARRAY: Target Effect
Effect of the angular and energy loss straggling on the θ , Ex
X
Y
Z
Target thickness
0.5 mg/cm2
1 mg/cm2
2 mg/cm2
Source of protons @ (0,0,0)
Strip pitch and thickness fixed = 1mm , 300μm
PARTICLE ARRAY: Angular Resolution (target in)
PARTICLE ARRAY: Ex Resolution (target in)
Ex ~ 140 keV (0.5mg/cm2) Ex ~ 170 keV (1mg/cm2) Ex ~ 225 keV (2mg/cm2) @4MeV
At high energies, emission angles close to 90 degrees, protons see more material
PARTICLE ARRAY: Excited States (no target)
133Sn
853.7 keV
1560.9 keV1655.7 keV
2004.6 keV
3700 keV
E (keV) FWHM
gs 174 keV
1560.9 181 keV
1561+1655 224 keV
2004.6 208 keV
3700 217 keV
132Sn(d,p)133Sn*
Excitation energy resolution reconstructed from the proton energy
PARTICLE ARRAY: Excited States (target in) 132Sn(d,p)133Sn*
0.5 mg/cm2
1 mg/cm2 2 mg/cm2
Effect of the target thickness in the Energy-Angle distributions:
Punch-through at lower Ep
Low the Ep due to the energy loss ->threshold
Increases the Ep -> difficult to separate states
133Sn
853.7 keV
1560.9 keV1655.7 keV2004.6 keV
3700 keV
1 mg/cm20.5 mg/cm2
PARTICLE ARRAY: Excited States (target in)
Target thickness worsens the resolution in Ex
PARTICLE ARRAY: INTERACTION POINT
Assuming reaction can take place at any Z < Target Thickness
X and Y are defined by the beam spot size
1 mg/cm2 1 mg/cm2 +inter point
PARTICLE ARRAY: RANDOM INTERACTION POINT
The main source comes from the uncertainty on the z-coordinate
Beam spot size negligeable
FWHM
203 keV
221 keV
280 keV
315 keV
418 keV
E (keV) FWHM
gs 174 keV
1560.9 181 keV
1561+1655 224 keV
2004.6 208 keV
3700 217 keV
133Sn
853.7 keV
1560.9 keV1655.7 keV
2004.6 keV
3700 keV
FWHM
362 keV
406.5 keV
778 keV
-----
945 keV
EXPERIMENTAL DATA: 132Sn(d,p)133Sn at Oak RidgeCourtesy K. JONES preliminary
Data will be an input for the event-generator ->Realistic implementation of the cross sections
160 um/cm2 target of CD2 at 4.7 MeV/u
132Sn(d,p)133Sn at 10 AMeV
Gamma array (simulations)
GAMMA ARRAY: VALUES OF GAMMA RAYS IN THE LAB : DOPPLER SHIFT
)cos1( labEE
Θlab(degrees)
~ 0.2 -> 10 AMeV
E=4 MeV -> [3.4,4.8] MeV
~ 0.3 -> 35 AMeVE=4 MeV -> [2.9,5.4] MeV
E/E tot ~ E/E int + E/E dop
GAMMA ARRAY: RESOLUTION: DOPPLER
BROADENING
Θlab(degrees)
E/
E
(%)
E lab = f(θ,) -> E/E dop ~ f(θ)
)cos1( labEE
E/E ~ 0.5 %
E=1MeV -> 5 keV
θ~ 2o
D=8 cm
Crystal Size θ
2.8 mm 2o
3mm for a detector size of 12cm ->40x40 =1600 ch detector
6 detectors ->6x 1600=9600 channels
GAMMA ARRAY: RESOLUTION: INTRINSIC
E/E int ~ Eγ)g(material
A
EγEoεscint
εph.
2.35
F. Notaristefani NIM A480 (2002) 423-430
Other materials:
LaBr3(Ce),LaCl2
To be studied
E/E int ~ 13.4 % at 662 keV ~ 90keV
Z
X
Y
GAMMA ARRAY: SIMPLE GEOMETRY
INPUT:
Distance to (0,0,0) = 5 cm
Area =10*10 cm2
Detector Thickness =3 cm
Source of gamma rays placed at (0,0,0)
GAMMA ARRAY: Gamma resolution
Meausrement of gamma rays in coincidence with particle is mandatory when dealing with thick targets.
GEOMETRY : Preliminary
M. Labiche
FURTHER WORK
Study of different materials for the Calorimeter
Implement realistic cross sections in the event-generator
In-beam test with the TIARA+MUST2+EXOGAM+VAMOS array
Implement realistic geometry to determine efficiencies
200 μm thick
400 μm thick
15000 μm thick
~ 40 times thicker t
The tickness determines the upper limit in Total energy and angle before the particles punch-through.
The energy rises steadily and therefore not much gain in angular distributions
PARTICLE ARRAY: Thickness detector
PARTICLE ARRAY: Ex Resolution
Ex=f(Ep,θ)