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: 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: 78 Ni(d,p) MeV/u 132 Sn(d,p) MeV/u 133 Sn keV keV keV 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, LaBr 3 )

(d,p) with 20 O and 26 Ne 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/GANIL September – November 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 20 O-> Location of the d 3/2 state in Oxygen neutron rich isotopes 26 Ne->Reveal isomeric f 7/2 intruder that competes with sd ground state

Triple coincidences: Target-like particles – TIARA/MUST2 Beam-like particles - VAMOS Gammas - EXOGAM Trigger: hit in Si-detector B. Fernández-Domínguez Preliminary design work required: IN-BEAM TESTS TIARA silicon array VAMOS spectrometer GANIL radioactive beam - 20 O (SPIRAL) 10.9 A MeV CD 2 target 0.5 mg/cm 2 Detectors  E, E, TOF B ,  EXOGAM Gamma-ray array 10 4 pps MUST2 Si-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. ( deg) - Hyball, 6 wedges, x16 rings (radial), x 8 sectors (azimutal) (  E~ 50 keV,  θ ~2 deg) ( 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 x128x128 Energy, position.  E~ 50 keV,  θ ~0.22 deg (pitch size 0.7mm at 180 mm) CsI- 4 modules with 4x4 crystals Identification  E-E

TIARA+MUST2 coupled to VAMOS B. Fernández-Domínguez Identification of the recoil VAMOS: Ionisation Chamber->  E Plastic ->E, TOF Drift Chambers ->X,Y, θ, 

TIARA+MUST2 coupled to VAMOS +EXOGAM B. Fernández-Domínguez Gamma detection with EXOGAM 4 90 deg 15% photopeak 1.3 MeV

SPIRAL: RADIOACTIVE BEAM of 20 O: d( 20 O,p) 21 O  21 O +  B. Fernández-Domínguez Preliminary (on-line results) BOUND STATES (d,p) E (MeV) θ (degrees) g.s 1 st 1.28 MeV SIMULATION Geant4 θ (degrees) E (MeV) g.s

B. Fernández-Domínguez SPIRAL: RADIOACTIVE BEAM of 20 O: d( 20 O,p) 21 O  20 O + n θ (degrees) E (MeV) UNBOUND STATES (d,p) SIMULATION Geant4 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

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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 Y INPUT: 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/cm21 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 gs174 keV keV keV keV keV 133 Sn keV keV keV keV 3700 keV FWHM 362 keV keV 778 keV keV

EXPERIMENTAL DATA: 132 Sn(d,p) 133 Sn at Oak Ridge Courtesy 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 Θ lab(degrees)  E  /E  (%) E  lab = f( θ,  ) ->  E  /E  dop ~ f( θ )  E  /E  ~ 0.5 % E=1MeV -> 5 keV  θ ~ 2 o D=8 cm Crystal Size  θ 2.8 mm 2 o 3mm for a detector size of 12cm ->40x40 =1600 ch detector 6 detectors ->6x 1600=9600 channels

GAMMA ARRAY: RESOLUTION: INTRINSIC  E  /E  int ~ F. Notaristefani NIM A480 (2002) Other materials: LaBr3(Ce),LaCl2 To be studied  E  /E  int ~ 13.4 % at 662 keV ~ 90keV

23 O from USD shell model and M.Stanoiu et al., PRC 69 (2004) Ne preliminary result. The energy of the 1d 3/2 neutron orbital rises when protons are removed from its spin-orbit partner, the 1d 5/2 orbital excitation energy (MeV) atomic number 1d 3/2 1d 5/2 1f 7/2 2s 1/2 27 Mg 23 O 25 Ne TRANSFER 24 Ne(d,p  ) 25 Ne : Systematics of the 3/2+ in the N=15 isotones