direct reactions at eurisol in the light of the tiara+must2 campaign at ganil b....
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Direct Reactions at Eurisol
In the light of the TIARA+MUST2 campaign at
GANIL
B. Fernández-Domínguez
Physics Motivation
Direct reactions are a unique tool to uncover and investigate new manifestations of nuclear structure of exotic nuclei
B. Fernández-Domínguez
-Inverse kinematics Detection:
- light charged particles - gamma-rays - neutrons - beam-like particles
Elastic and inelastic scattering -> nuclear and transition densities
Transfer, knock-out and break-up reactions -> microscopic shell-structure
EURISOL FW5 report : SCIENTIFIC CASE (Appendix A):
Array for light charged-particle and gamma-array
measurements: GRAPA (Gamma-Ray And Particle Array)
Instrumentation for Direct Reactions
B. Fernández-Domínguez
• Charged Particles: (Particle Array )
Solid-angle of 4
x~0.1,0.5 mm and θ~ 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
EURISOL FW5 report : INSTRUMENTATION (Appendix E):
Updated version: http://ns.ph.liv.ac.uk/eurisol/spec_expts/M2.1_apparatus.pdf
Integration of cryogenic and polarised targets.
RIB
- SIMULATIONS: Modelling of a number of potential key experiments proposed, study different configurations etc…
- IN-BEAM TEST TO VALIDATE DESIGN CHOICES : To asses the methodology and feasibility of the design concept.
B. Fernández-Domínguez
Preliminary design work required
SIMULATIONS:
Key experiments:
• 78Ni(d,p)79Ni @ 10 MeV/u
• 132Sn(d,p)133Sn @ 10 MeV/u
133Sn
853.7 keV
1560.9 keV1655.7 keV
2004.6 keV
3700 keV
Preliminary design work required: SIMULATIONS
Target Thickness
Particle Array: (energy and angular resolution)
Gamma Array:
Interaction Point
B. Fernández-Domínguez
Scintillating material : (CsI, LaBr3)
(d,p) with 20O and 26Ne beams at SPIRAL : Study of the N=16 shell gap
B. Fernández-Domínguez
Large step towards an integrated particle-gamma ray array.
TIARA-MUST2 CAMPAIGN AT SPIRAL/GANILSeptember – November 2007
-Si-array ->Array of silicon detectors covering 90% of 4pi. MUST2 and TIARA
-Ge-array->EXOGAM
-Spectrometer ->VAMOS
Results can be used to validate the design choices of the new EURISOL array
Preliminary design work required: IN-BEAM TESTS
20O-> Location of the d3/2 state in Oxygen neutron rich isotopes
26Ne->Reveal isomeric f7/2 intruder that competes with sd ground state
Triple coincidences:Target-like particles – TIARA/MUST2Beam-like particles - VAMOSGammas - EXOGAMTrigger: hit in Si-detector
B. Fernández-Domínguez
Preliminary design work required: IN-BEAM TESTS
TIARAsilicon array
VAMOSspectrometer
GANIL radioactive beam - 20O (SPIRAL) 10.9 A MeV
CD2 target0.5 mg/cm2Detectors
E, E, TOFB,
EXOGAMGamma-ray array
104 pps
MUST2Si-CsI
TIARA: Inner and Outer Barrel +Hyball
B. Fernández-Domínguez
TIARA – Two Barrels: 8 detectors, x 4 longitudinal strips each. -Inner Barrel-> Energy, position. (E~ 200 keV, θ~1-2 deg)-Outer Barrel- identification. (30-140 deg)
- Hyball, 6 wedges, x16 rings (radial),
x 8 sectors (azimutal) (E~ 50 keV, θ~2 deg)
(150-175 deg)
MUST2: 4 Telescopes of Si+CsI
B. Fernández-Domínguez
MUST2 4 telescopes of Si-CsI placed at forward angles. (0-30 deg)
Si-Strip – 4 modules x128x128Energy, position.E~ 50 keV, θ~0.22 deg (pitch size 0.7mm at 180 mm)
CsI- 4 modules with 4x4 crystalsIdentification E-E
TIARA+MUST2 coupled to VAMOS
B. Fernández-Domínguez
•Identification of the recoil VAMOS:Ionisation Chamber->EPlastic ->E, TOF Drift Chambers ->X,Y,θ,
TIARA+MUST2 coupled to VAMOS +EXOGAM
B. Fernández-Domínguez
•Gamma detection with EXOGAM4 Clovers @ 90 deg
15% photopeak efficiency @ 1.3 MeV
SPIRAL: RADIOACTIVE BEAM of 20O: d(20O,p)21O 21O +
B. Fernández-Domínguez
Preliminary (on-line results)
BOUNDSTATES
(d,p)
E (
MeV
)
θ (degrees)
g.s
1st 1.28 MeV
SIMULATIONGeant4
θ (degrees)
E (
MeV
)
g.s
B. Fernández-Domínguez
SPIRAL: RADIOACTIVE BEAM of 20O: d(20O,p)21O 20O + n
θ (degrees)
E (
MeV
)
UNBOUNDSTATES
(d,p)
SIMULATIONGeant4
E (
MeV
)
θ (degrees)
E (keV)
Preliminary (on-line results)
Simulations reproduce response of arrays and give insight into the main parameters that contribute to performance
Online analysis of the experiment confirms we can study different reactions channels, obtain level energies and l-values information
The feasibility of the methodology is demonstrated.
SUMMARY
• transfer to bound and unbound states with full channel identification• triple coincidences with excellent gamma energy resolution• also have (d,d’) and (d,t) acquired simultaneously with TIARA and MUST2 • to include unbound states requires the large VAMOS angle/momentum bite• type of experiments will be important to learn for the future array.
FUTURE Increase efficiency of particle-gamma coincidences..
Gamma detection better efficiency, allow for fast-particle detection simultaneously
Improve performance of particle array. (Energy resolution, low thresholds)
Possibility to introduce cryogenic or polarised targets
No part of the talk
end
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: 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
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
EγEo
εscintεph.
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
• 23O from USD shell model and M.Stanoiu et al., PRC 69 (2004) 034312.• 25Ne preliminary result.
The energy of the 1d3/2 neutron orbital rises when protons are removed from its spin-orbit partner, the
1d5/2 orbital.
4.5
1.5
1.0
0.5
0.0
3.0
2.5
2.0
4.0
3.5
exci
tati
on e
nerg
y (M
eV)
6 8 10 12
atomic number
1d3/2
1d5/2
1f7/2
2s1/2
27Mg23O 25Ne+2.1 TRANSFER 24Ne(d,p)25Ne : Systematics of the 3/2+ in the N=15 isotones