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
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->Obervables
Ep and/or E ->Ex
θp -> dσ/d -> (l , SF)
θ_lab(deg)
En
erg
y (M
eV)
B. Integrated particle and gamma detection system : Direct reactions studies
PARTICLES TO BE DETECTED :
• Beam-like particles
Spectrometer
• Charged Particles
Particle Array
Solid-angle of 4
PID with (x~0.1,0.5 mm and ~ 1-5 mrad)
Large dynamic range with PID to Z=10• Gamma and fast charged particles
Gamma Array
Solid-angle of 4
Best efficiency and resolution
PID with (x~0.1,0.5 mm and ~ 1-5 mrad)
Particle ArrayGamma Array
RIBs Ancillary detectors:Spectrometer,
Neutron array, …
PARTICLE ARRAY: Simple Geometry
Distance to (0,0,0) = 5 cm
Box of 4 Silicon detectors :
Area =10*10 cm2
Detector Thickness =400um
Isotropic source: protons 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: Energy Resolution
En
erg
y (M
eV)
θ_lab(deg) θ_lab(deg) θ_lab(deg)
10 keV 50 keV 100 keV
Energy and angle correlated -> need to fix one variable, Eproton
Ep=2,3,4,5,6 MeV -> θ and Ex (FWHM)
E= 50 keV reasonable value
PARTICLE ARRAY: Angular Resolution
Unnoticeable dependence with the strip sizes explored.
If Strip pitch ~ 1mm ->number of channels for 10 cm detector 100*100=10000
6 detectors =6x10000 channels (pad-type detector)
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: 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
Isotropic source of protons @ (0,0,0)
Strip pitch and thickness fixed = 1mm , 400μm
PARTICLE ARRAY: Angular Resolution (target in)
At high energies, emission angles close to 90 degrees, protons see more material
PARTICLE ARRAY: Ex Resolution (target in)
Ex ~ 140 keV (0.5mg/cm2) Ex ~ 170 keV (1mg/cm2) Ex ~ 225 keV (2mg/cm2)
for 4MeV
PARTICLE ARRAY: Excited States (target in)
79Ni
1 MeV
2 MeV
78Ni(d,p)79Ni * (Ex=1,2 MeV)
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
FURTHER WORK
Study of the influence of the interaction point
Full geometry implementation of the integrated charge particle and gamma particle
Cross Sections implementation
Reconstruction with CsI
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 ~ 50 keV
Distance to (0,0,0) = 8 cm
Array of CsI detectors :
Area =10*10 cm2
Detector Thickness = 20 cm
Isotropic source gammas 1MeV at (0,0,0)
GAMMA ARRAY: Simple Geometry
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