GAMMA-PARTICLE ARRAY FOR DIRECT REACTION STUDIES

SIMULATIONS

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, …

78Ni(d,p)79Ni @ 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 =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: Ex Resolution

Ex=f(Ep,θ)

Strip size small influence on the Ex resolution

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 (no target)

79Ni

1 MeV

2 MeV

78Ni(d,p)79Ni * (Ex=1,2 MeV)

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

PARTICLE ARRAY: Excited States (target in)

Thicker target worsens the resolution in Ex

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

78Ni(d,p)79Ni 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 ~ 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

FURTHER WORK

Study of different materials

Influence of the particle detector in the gamma detection system