Status of the magnetic spectrometer PRISMA

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1 Status of the magnetic spectrometer PRISMA E. Fioretto INFN Laboratori Nazionali di Legnaro 1

PRISMA in vacuum mode Dipole 50 cm 120 cm 60 +130 Quadrupole 30 cm Beam Target 2-20 Rotating platform

2 PRISMA in vacuum mode Dipole 50 cm 120 cm Quadrupole 30 cm Beam Target 2-20 Rotating platform PRISMA: a large acceptance magnetic spectrometer Ω 80 msr; Bρ = 1.2 Tm ΔA/A ~ 1/200 Energy acceptance ±20%

3 PRISMA : the Start detector Quadrupole Dipole Target Δt ~ 350 ps, ΔX, ΔY ~ 0.5 mm Y MCP X G. Montagnoli et al. NIM A547, 455 (05) 3

4 PRISMA : the Focal Plane Detector Quadrupole Dipole Target S. Beghini et al. NIM A551, 364 (05) MWPPAC X position Δt ~ 300 ps, ΔX, ΔY = 1 mm 4

5 PRISMA : the Focal Plane Detector Quadrupole Dipole Target ΔE/E < 2% Z/ΔZ ~ 60 for Z=20 70 Zn+ 238 U Ionization chamber Z=30 5

6 CLOVER array (up to March 2008) Quadrupole Dipole 23 EUROBALL Clovers Efficiency ~ 3 % (E γ = 1.3 MeV) FWHM = 0.9% (for β=10%) Peak/Total ~ 45% CLARA 6

Main topics of the PRISMA-CLARA campaign Grazing reactions as a tool to study n-rich n nuclei Shell evolution @ N=20/32/34/50/82 Collectivity

7 Main topics of the PRISMA-CLARA campaign Grazing reactions as a tool to study n-rich n nuclei Shell N=20/32/34/50/82 Collectivity (deformation) and dynamical symmetries Lifetime measurements Pairing vibrational states Molecular resonances Multinucleon transfer reactions 7

8 Around the island of inversion 36 S MeV X. Liang et al., PRC 74, (2006) PRISMA θ=56 36 Si CLARA (6 + ) (4 + ) E γ (kev) rotor vibrator 8

Exploring the 48 Ca region RDDS method 48

0% d Target 48 Ca @ 310MeV Mass resolution

9 Exploring the 48 Ca region RDDS method 48 Ca θ g for BLF PRISMA E γ CLARA E γ nat Mg 208 Pb β 8.0% Degrader β 10.0% d Target MeV Mass resolution after degrader is preserved Differential Plunger E γ E γ E γ : Doppler corrected 9

10 Exploring the 48 Ca region Transition probabilities 50 Ca τ = 96 ± 7 ps ( E2 : 2 0 ) = e 2 fm B ± I s I u 51 Sc τ = 25 ± 4 ps B 4 ( E2 : 11/ 2 7 / 2 ) = 24 ± 4 e 2 fm Ca (2 + ) The measured transition probability in 50 Ca is lower than in doubly-magic 48 Ca, in agreement with shell-model calculations (tuned with previous experiments in the mass region) J.J. Valiente-Dobón et al., LNL Annual Report 2007 and to be published 10

11 Spectroscopy of heavy Cr isotopes 64 Ni MeV N. Mărginean et al., PLB 633 (2006) 696 γ rays from the yrast levels of 58 Cr observed for the first time 11

12 γ-softness in heavy Cr and Fe isotopes 64 Ni MeV 58 Cr PLB 633 (2006) 696 N. Mărginean et al., F.Iachello PRL85, 3580 (2000) The R(E4/E2) ratio for the heavy Fe isotopes is very close to the 2.50 value characteristic of γ-soft rotors (S. Lunardi et al., PRC 76, (2007)) 58 Cr lies exactly at the 2.20 value predicted for the E(5) dynamical symmetry. The energies of the yrast band are in good agreement with the predictions. 12

13 Summary of the PRISMA-CLARA campaign Scientific output 24 experiments (Jan Mar 2008) 16 papers + 2 submitted Over 40 presentations at international conferences/workshops User Access ~ 50% of the total beam-time of the Tandem/PIAVE-ALPI accelerator complex of INFN-LNL ~ 200 European users most of them supported within the Transnational Access activity of the EC-contract EURONS Education 8 thesis (diploma, PhD, ) Support (research contracts) 8 person-years funded by INFN 5 person-years for Nuclear Structure Based Facilities funded by EC through EURONS (only partly devoted to PRISMA-CLARA) 13

triple-clusters 36-fold segmented crystals 555 digital-channels Eff. 3 7 % @ Mγ = 1 Eff.

test site: LNL PRISMA + AD + Plunger PRISMA + CLARA + Plunger 23 LOIs 16 Institutions The

14 The AGATA demonstrator at LNL CLARA vs. AD LN 2 line Support frame Telescopic beam line 1 symmetric triple-cluster 5 asymmetric triple-clusters 36-fold segmented crystals 555 digital-channels Eff. 3 7 Mγ = 1 Eff. 2 4 Mγ = 30 Full DAQ with on-line PSA and γ-ray tracking In beam Commissioning First test site: LNL PRISMA + AD + Plunger PRISMA + CLARA + Plunger 23 LOIs 16 Institutions The first subset of AGATA (the Demonstrator Array) will soon start operation at the Laboratori Nazionali di Legnaro. The installation is in progress. 14

15 PRISMA in Gas-Filled mode The new detector-chamber mounted on PRISMA Gas-flow control system Magnetic dipole Detector chamber for GFM 15

16 PRISMA in Gas-Filled mode Problems with magnetic rigidity 1,9 16 PRISMA max rigidity for central trajectories cross sections are known, so it is an ideal case for validating the simulations the average charge state can be very low in gas for a slow, heavy ion Bρ 1. 2Tm for a central trajectory Prisma is limited to A<180 by using non-central trajectory we can reach Bρ = 1.5 Tm Bρ (Tm) 1,7 1,5 1,3 1,1 0,9 0,7 112 Sn 252Fm 148 Sm 0,5 0,01 0,10 1,00 10,00 E/A (MeV/amu) <q> according to Betz 58 Ni 208 Pb 176 Hf

17 Recoil detectors Si-strip detectors for PRISMA in GFM 2 x 3 SSD, 300 μm thick, 5x5 cm 2 16 resistive strips 17

18 Recoil detectors and electronics 3mm Home-made PA Junction side ohmic side 16 PA box (1 Si detector) Total of about 100 signals 18

19 Scattering chamber monitor beam stopper CF window nose GSI windows (gas side) beam Conditions of the beam test LNL windows beam side 19

20 In-beam tests Elastic scattering reaction below Coulomb barrier 58 Ni MeV, 55 the heavy recoils simulate typical ERs without the complications of a 0 measurement cross sections are known, so it is an ideal case for validating the simulations it is also possible to measure the position spectrum of the beam Measurements varying the dipole field, for each pressure centering the ER onto the FPD varying the quadrupole field for best transmission and resolution different gas pressures (1 mbar and 3 mbar) tests with different gas would also be of interest 20

21 In-beam tests (June-July July 2007) X-Energy matrix and position spectrum cont α-calibration fwhm ~ 15cm 0,07 0,12 0,17 0,22 BD (a.u.) 21

22 Summary of performed tests PRISMA in GFM Adequate Bρ up to masses A~200 Focal plane detector : 6 Si strips detectors cm 2 Aim : fusion reactions studies (no SHE) Tests performed Electronics tests with Si and α-source C-foil window leak tested with different gases In-beam tests 58 Ni (160 MeV)+ 197 Au, 55 (July 07) Test of spot size beam separation vs energy and gas Future step In beam 0 to measure a fusion reaction in full operating condition 22

23 Summary PRISMA+CLARA 24 experiments (Jan Mar 2008) ~ 200 European users ~ 50% of the total beam time of the Tandem/PIAVE-ALPI accelerator complex PRISMA+AGATA Demonstrator The installation of the AGATA Demonstrator around the target area of PRISMA is in progress (EURONS JRA02-AGATA) The first experimental campaign for reaction mechanism and nuclear structure studies with PRISMA+AD in 2009 PRISMA in GFM (EURONS JRA06-INTAG) Recoil detector and home-made electronics successfully tested with PRISMA 0 23

The heavy-ion magnetic spectrometer PRISMA

Nuclear Physics A 701 (2002) 217c 221c www.elsevier.com/locate/npe The heavy-ion magnetic spectrometer PRISMA A.M. Stefanini a,,l.corradi a,g.maron a,a.pisent a,m.trotta a, A.M. Vinodkumar a, S. Beghini