Magdalena Kowalska, CERN PH-SME-IS ISOLDE scientific coordinator’s report INTC meeting, November 4, 2010 Running period 2010 highlights problems Accelerator schedule 2011 Long shutdown (2012 or 2013) Magdalena Kowalska, CERN PH-SME-IS

ISOLDE experiments and requests 2010 INTC February 2010 5 new experiments: IS499 – IS503 132 approved RIB shifts (out of 183 requested) 8 experiments completed (3 REX experiments): IS381, IS414, IS415, IS417, IS418, IS425, IS431, IS469 69 active experiments for 2010 beam period INTC June 2010: 34 HIE LOIs INTC November 2010 189 shifts requested in new proposals and addenda 21 shifts requested by LOIs

ISOLDE schedule 2010 (May 6 - Nov 21) ~29 weeks for physics vs 31 weeks in 2009 Requested shifts: 667 in total 93 different beams 627.5 for 50 experiments GPS HRS Scheduled shifts (~73%): 480 in total 75 different beams 443 for 41 experiments REX-ISOLDE: 432 shifts requested 160 shifts scheduled (~37%) 11 experiments (7 runs) additional WITCH runs (need REXTRAP)

IS480 Charge radii of n-deficient Mg isotopes at COLLAPS Now differences in Mg charge radii known all across sd shell for 21-32Mg HFS structure of 21Mg observed in beta-decay asymmetry D. Yordanov

IS501: Mossbauer studies Sn4+ Sn2+ 57Mn beams & (briefly) 119In @ 40kV 2nd chance with 119In Very successful 57Mn run. Running at 40kV was new and untested, but works (not the case with 30kV). More than 2000 spectra taken (a record) and many surprises in the data, with ongoing analysis. First time since early 1980s that 119In has been used as a Mossbauer probe at ISOLDE. 119In (T½ = 2.4 min) has very similar lifetime to the 57Mn (T½ = 1.5 min work-horse, but very different chemistry. Some things should say the same story while others a different story. In particular: Sn has more ”clear-cut” valence dependence. In Fe, electronic configuration can give complications. Sn4+ Sn2+ Results from Al2O3 - Initial (and surprising) main result: - Spectra are dominated by Sn4+ (d = 0.07(1) mm/s - Also seems to be the case for all oxides measured: why? (Sn4+ is not the natural valence state... ) => An explanation may be given at the ISOLDE Workshop K. Johnston et al.

IS430 Most intense 11Be beam (for 10 days) behind REX used with T-REX setup Excitation spectra from particles d(11Be,p)12Be d(11Be,d)11Be d(11Be,t)10Be 1/2- 2+ 2+ 1- 0+ 2- 1- 0+ 2+ 0+ Gamma spectra 1/2+->1/2- 1-->2+ 2+->0+ 0+->2+ 2+->0+ 1-->0+ K. Riisager, J. Johansen

Mn for SSP 56Mn in GaAs (s.i., n+ and p+)‏ L. Pereira, G. Correia Mn-doped GaAs: most well understood dilute magnetic semiconductor (DMS)‏ Potential application in spintronics challenge: increase TC above RT Known: Mn takes substitutional and interstitial lattice sites Interstitial vs. substitutional fractions controls TC General belief: Low thermal stability of interstitial Mn (~200 ºC with activation energy of 0.7 eV)‏ 56Mn in GaAs (s.i., n+ and p+)‏ L. Pereira, G. Correia 56Mn in Ga1-xMnxAs (MBE grown with stable 55Mn)‏ Direct identification of the Mn interstitial site Evidence of high thermal stability of interstitial Mn Possible implications on the strategies and prospects to increase TC in Mn-doped GaAs

IS475 224Ra Coulomb excitation ~105 ions/s at target, REX efficiency ~1%, q=52+ for Ra 4+ → 2+ 2+ → 0+ X-rays L. Gaffney and P. Butler 6+ → 4+ 3- → 2+ 7-→ 5- 8+ → 6+ 5- → 4+ 1- → 0+

IS499 44Ar at T-REX: CO2 and Kr contamination not a problem New states identified Very good yield for 10 days

12Be at Collaps Charge radius of 12Be, to be compared with 7-11Be, measured also at COLLAPS 12Be optical resonance Record yield of 12Be at ISOLDE (1e4 ions/1uC)

199Hg and Hen Egg White Protein - IS488 … 199Hg and Hen Egg White Protein - IS488 Enzyme which destroys bacterial cell wall In physiological conditions: folded into a compact structure Non-metal binding protein No experiments ever done with heavy metals and this protein Results: It can bind Hg(II), however, this changes its structure dramatically Does protein preserves its functionality? Binding of Hg(II) most likely speeds up the protein folding Catalytic function of Hg(II)

Main problems in 2010 (I) TISD on Sm RILIS and target test: no laser ionised Sm visible SSP collections with YO HP target: Strong stable contamination, not much physics output, but promising yields of Fe and Cr beams GPS HRS YO CP target for 1st REX-ISOLDE run: 9C yield dropped quickly after start – run not successful – need target tests ZrO target with RILIS for Ga at COLLAPS: Target broken right before on-line run – cancelled WITCH run on Ta W target: Very contaminated rare-earth beam, but some recoil spectra (on mixed beam) could be recorded Miniball run on 72Kr from YO CP target: 10-fold yield drop within a few days, strong 72Ge contamin.

Main problems in 2010 (II) Pb HP target for SSP collections: GLM deflection plates blocked (broken pinion); no beam for users ISOLTRAP run with UC CP target: No 46,47Ar visible among very strong stable contamination of SC(H). No masses measured but multi-reflection isobar separator commissioned . GPS HRS 96Kr Minball run with UC CP target: many contaminants and weak Kr signal at Miniball but 96Kr E(2+) observed in 2009 confirmed 202Rn Miniball run: target broke in the middle of the run; only partial statistics collected 220Rn Miniball run: cancelled due to target failure during 202Rn run

Main problems in 2010 (III) 70-72Kr from YO CP target for ISOLTRAP: No beams visible among large Cl contamin. but more tests with multireflection isobar separator 30Na from UC W target to Miniball: measured yield and counts at Miniball much below database value. Beam given to next user. GPS HRS Mn beam for Mossbauer studies (UC Ta): GPS HV trips above 30kV (requested HV>50kV). Extraction electrode exchanged and 40kV allowed very good results. N-rich rare earths at ISOLTRAP (Ta W): no beam of interest found among stronger contamination. Another new mass measured. Tests of high-density UC target: GPS turbo fans go off. Pumps will probably survive only 3-4 days.

Accelerator schedule 2011 (draft) ISOLDE dates (still prelimin.) protons to ISOLDE April 25 physics start ISOLDE May 2 protons stop November 20 (i.e. 29 weeks for physics vs 29.5 in 2010) Shutdown period used for new GPS front-end Several 24h injector stops every 6 weeks. Several long periods of machine development partly with parasitic beam to ISOLDE (not guaranteed)

Long CERN-wide shutdown One year shutdown of CERN accelerator complex (to save money and manpower) planned for 2012 However: - LHC runs better than expected CERN/LHC competitor Fermilab might run after 2011 nobody is happy about the exact date of the shutdown It is very probable that shutdown is postponed to 2013, which will be better for ISOLDE and HIE-ISOLDE. (Decision will be taken in late spring/early summer 2011.) ISOLDE planning/running with 1-year shutdown at 2012 or 2013: go ahead with GPS front-end exchange in 2010/2011 shutdown priorities for scheduling in 2011: as normal (experiments waiting for beam longest) + projects for a PhD thesis (in case shutdown takes place in 2012) INTC accepts regular proposals in February 2011 (June and November to be discussed) some weeks of offline physics

New ISOLDE web page Online since September 2010: changes in layout and content missing info is filled up step by step some new elements, like NEWS