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)