Jose Javier Valiente Dobón LNL (INFN) Ancillary devices for spectroscopy with Quasi-Elastic and Deep-Inelastic Collisions. Jose Javier Valiente Dobón LNL (INFN)

Overview Need of an ancillary heavy ion detector. Ancillary detectors based on PPACs. The Pyramid, Liverpool-Daresbury and CHICO detectors. The new DANTE array at LNL. An ancillary heavy ion detector for SPIRAL2 Summary.

Requirements of a heavy ion detector Need of Heavy Ion Detectors Detection of scattering angles  determine reaction kinematics Heavy-ion γ-ray coincidence  Doppler correction event-by-event basis Requirements of a heavy ion detector Resistant to radiation damage Minimize absorption losses Good position resolution Small dimension γ TLF BLF Beam Target HPGe θ

Ancillary detectors based on PPACs Trapezoidal form to maximize solid angle, Ω=1.8π Constant gas flow of isobutane Resistive cathode made of low absorption material Position Resolution ∆Θ=∆φ= 1-2o Pyramid Liverpool-Daresbury One annular backscatter detector Six trapezoidal forward detectors Constant gas flow of isobutane Small γ attenuation Resolution ∆Θ=1o, ∆φ=10o (forward) K. Vetter et al., NIM A344, 607 (1994). A.J. Cresswell et al., PRC51, 1025 (1995).

Gammasphere Beam CHICO Beam Target Rates 100 k/s Trapezoidal form, 10 azimuthal sections. Solid angle Ω=2.7π Segmented delay-line cathodes Segmented anodes asymmetrically Position Resolution: ∆θ=10, ∆φ=90 TOF resolution 500ps; Δm/m=5% M.W. Simon et al., NIM A452, 205 (2000).

Fragment Identification Position determination Fragment Identification Segmented asymmetrically 198Pt + 136Xe @ 850MeV LBNL Coincidence two co-planar anode pairs (resolution φ=90): Large-Large Large-Small Small-Large

Doppler corrected γ spectra for TLF Spectra Os isotopes, gated on Ba isotopes (binary partners).

PRISMA: Large acceptance Magnetic Spectrometer CLARA-PRISMA setup Quadrupole Dipole Start detector X-Y, time IC 6m (TOF) G.Montagnoli et al. LNL annual Report 165 (2000). Position sensitive MCP E-ΔE MWPPAC X-Y, time ΔΩ = 80 msr ΔZ/Z  1/60 (Measured) ΔA/A  1/190 (Measured) Energy acceptance ±20% Bρ = 1.2 T.m Angular range 30o - +130o PRISMA: Large acceptance Magnetic Spectrometer

25 Euroball Clover detectors CLARA setup PRISMA-CLARA results 82Se+238U @ 505 MeV (Θgrazing=64o) Gate on 80As (-1p -1n) Level scheme from a thick target GASP exp. 460 MeV 82Se on 192Os Nucleus completely unknown previously! Reaction Chamber 25 Euroball Clover detectors Efficiency~3%

DANTE (Detector Array for multi Nucleon Transfer Ejectiles) Start detector of PRISMA  No possible to place PPACs Limited efficiency of the PRISMA-CLARA setup  No γ-γ coincidences. DANTE (heavy ion detector based on MCP) reveals the position interaction of the recoils  Doppler correction. DANTE placed at the grazing angle, has a high efficiency  γ-γ coincidences  No need of an extra GASP experiment to build up a level scheme. 20° Versatile Beam CLARA PRISMA MCP (50x70mm) detectors Grazing angle 70°

First prototype of DANTE Thickness:13mm Preamplifier in vacuum Linea di ritardo MCP Lateral section of the first DANTE prototype Delay line

Test of the first DANTE prototype Time resolution 130ps (TAC-ADC) Position resolution <1mm Sustained high counting rated High noise rejection TOF X coordinate Y coordinate Amplitude

Heavy ion detector MCP based An ancillary heavy ion detector for SPIRAL2 The selection of the ancillary detector will depend on the spectrometer chosen for SPIRAL2 Heavy ion detector MCP based Radiation damage warranty: at least 1000 h under beam Different geometrical forms of the MCP in order to cover the Ω=4π Good performance: Position resolution and TOF Mass resolution for light fragments through kinematic coincidences (e.g. A ≤ 20) Relative low cost

Summary Some examples of heavy ion detectors based on PPACs : Pyramid, Liverpool-Daresbury and CHICO. DANTE array (MCP based detector) for the CLARA-PRISMA setup at LNL. Possible use of DANTE like detectors in the radioactive beam facility, SPIRAL2.

CLARA-PRISMA setup PRISMA A & Z identification “in-beam” γ-ray CLARA