The REXTRAP Penning Trap Pierre Delahaye, CERN/ISOLDE Friedhelm Ames, Pierre Delahaye, Fredrik Wenander and the REXISOLDE collaboration TAS workshop, LPC CAEN, 30/03/2004 Its potential use for nuclear spectroscopy?

The REX-ISOLDE facility Acceleration of exotic nuclei delivered by ISOLDE/CERN  Ion beam cooling in REXTRAP  Charge breeding in REXEBIS  Acceleration in the LINAC A/q≤4.5

Beam preparation at REX-ISOLDE REXTRAP and REXEBIS REXTRAP REX EBIS q/A- selector breeding time (A/q < 4.5) 20 ms beam intensities < 10 9 /s ions in one charge state < 30% injection efficiency into EBIS 40% efficiency REXTRAP 40% If the number of ions inside the trap is not too big (<10 7,10 8 ) If the charge exchange process is negligible

The REXTRAP Penning trap Cylindrical trap filled by Ne as buffer gas P. Schmidt et al, Nucl. Phys. A 701(2002)550

Radioactive ion beam manipulation Tests of the cooling methods EE Accumulation Cooling Ejection Sideband Cooling Quadrupolar excitation at  c =qB/M in the transverse plane of the trap Magnetron and cyclotron motions coupling Viscous force F = -  m v  r (t)  r(0) e -  /2 t example Na mbar Ne d = 400 s -1  cooling ≈20 ms

Emittance reduction with the Sideband cooling method trapped and ejected ions E 80% =30.1 .mm.mrad E RMS =9.4 .mm.mrad trapped and ejected ions E 80% =10.6 .mm.mrad E RMS =3.9 .mm.mrad Injection efficiency in REXEBIS 45% N ions <10 6 Sideband Cooling

Dipolar ExcitationQuadrupolar Excitation Rotating Wall cooling The Lorentz force compress the ion cloud B Rotating Wall cooling Interesting for high number of ions > 10 6

Quadrupolar excitation Dipolar excitation Resonance frequencies Excitation modes of the non neutral plasma Experimental results Dipolar excitation: #  z Quadrupolar excitation: #  z,  c 39 K + ions Resonance frequencies zz cc Rotating wall cooling

Sideband excitation  Noble gases: high ionization energies Losses due to the charge exchange process Charge exchange investigation 40 Ar + ions 78 Kr + ions 130 Xe + ions Quantitative information about charge exchange cross sections?

Nuclear spectroscopy experiments at REX-ISOLDE Radioactive EXperiments at ISOLDE The MINIBALL detector: 8 Germanium clusters Coulomb excitation and nucleon transfer reactions to probe the structure of the exotic nuclides Last year:  30,31,(32) Mg B(E2,0 + ->2 + ) N=20  72,74,(76) Zn B(E2,0 + ->2 + ) 40≤N≤50  6,7,8,9(11) Li 11 Li Polarizability  88 Kr B(E2,0+->2+) Progress in Particle and Nuclear Physics 46(2001)389

Beam developments with REXTRAP Molecule breakup in the buffer gas  SeCO + Shape coexistence around mass 70  AlF + Study of the stellar reaction 14 O( ,p) 17 F  SnS + B(E2,0+->2+) towards doubly magic 100 Sn New beams available! Preliminary result: F + with 20% efficiency

In-trap spectroscopy In-trap conversion electron spectroscopy L. Weissman et al, NIM A 492(2002)451 Study of the feasibility of such spectroscopy technique Cooled pin diode B=3T Trap center Advantages:  high efficiency  no implantation  Can be used for ion cloud imagery Drawbacks:  60 keV background, low energy background  charge space induce resolution limitations  buffer gas pressure limitation  Detector in a high magnetic field Tests with well known electron sources: 116m2 In, 118m2 In, 221Fr (  )

Conclusion REXTRAP as a first stage of REX-ISOLDE is an efficient and/or interesting setup for radioactive beam cooling (emittance reduction) beam developments  breakup of molecules  study of charge exchange process The possibility for conversion electron spectroscopy has been studied Strong technical limitations A dedicated setup could be more adapted