the INFN Italy EXOTIC group Milano, Napoli, Padova, NIPNE Romania, Crakow Poland. Presented by C.Signorini Dept. of Physics and Astronomy Padova (Italy): University and INFN STUDIES OF Dynamics of the interaction ad the Coulomb barrier induced by light loosely bound Radioactive Ion Beams produced at LNL Tandem Van de Graaff (ITALY) 17 F >10^5 Hz 7 Be >10^4 Hz 8 B >10^3 Hz PRESENTS: → →

Scattering of 17 O by 58 Ni at Coulomb barrier energies 1 – (new) Utilization Silicon Detectors with ASIC electronics Large reduction of electronics channels 2 – The physics case Interaction of loosely bound-radioactive nuclei at the Coulomb barrier. Its role played in the reaction cross section Comparison between the reaction cross sections induced by loosely bound (Radioactive Nuclei) and well bound (stable)

Problematic with RIB: projectiles LOOSELY or WELL BOUND Ni, Zn TARGETS WELL BOUND +17F LOOSELY BOUND ~ REACTION CROSS SECTION ~ BOMBARDING ENERGY

Si double sided, 2 mm strip, 32x32 strips, 64x64 mm 2, 300 micron thick by MICRON + two (slow, fast) commercial ASIC chips +home made 12bits multisampling ADC 8xSAMPLING AT 50MhZ Reaction cross section with 17 0 stable well bound S n = 4.1 MeV to be compared with 17 F unstable loosely bound S p =0.6MeV Mirror nuclei identical nuclear structure! EXPER. SET UP AND PHYSICS

ONE CHIP FOR 32 CHANNELS !!!! ASICS CHIPS ARCHITECTURE

Pu  - particle resolution ~ 85 keV

JUNCTION SIDE OHMIC SIDE  →→ Si detector 300  40 

17 O BEAM DIRECTION 2 DETECTORS IN BEAM EXPERIMENTAL SET UP

17 O SCATT. SPECTRA AT 82°, 58 Ni+ 208 Pb mixed target Resolution  E/E ≈ 1.2 % 208 Pb 58 Ni

Angular distributions theoretical fit via CC code FRESCO

Loosely bound: 8 B S p = MeV, 17 F S p = MeV Well bound: 17 O S n = MeV, 16 O S α = MeV Reaction cross sections vs. projectile energy in reduced scales. Target 58 Ni 8B8B 17 O 16 O 17 F

Comparison of reaction cross sections for loosely bound and well bound projectiles via different  react (E cm )  scaling approaches y (  react. ), x(E cm ) axis Scaled for different Coulomb Barrier and Radii y  react ), x(E cm ) axis Scaled ALSO for different Coulomb Barrier widths

CONCLUSIONS 1 – The utilization of commercial ASIC chips reduces succesfully the number of channels of around a factor >10 ! 2 – Energy resolution ~85 keV for   E/E ≈ 1.2% in beam,with 50 MeV 17 O 3 – 17 O well bound scattering has reaction cross sections not smaller than the similar loosely bound projectile 17 F. WHY ???