Magdalena Kowalska, CERN PH-SME-ISMagdalena Kowalska, CERN PH-SME-IS

ISOLDE scientific coordinator’s reportINTC meeting, November 4, 2010

Running period 2010highlightsproblems

Accelerator schedule 2011Long shutdown (2012 or 2013)

ISOLDE experiments and requests 2010ISOLDE 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)ISOLDE schedule 2010 (May 6 - Nov 21)

• 667 in total• 93 different beams• 627.5 for 50 experiments

Requested shifts:

• 480 in total• 75 different beams• 443 for 41 experiments

Scheduled shifts (~73%):

• 432 shifts requested• 160 shifts scheduled (~37%)• 11 experiments (7 runs)• additional WITCH runs

(need REXTRAP)

REX-ISOLDE:

GPS HRS

~29 weeks for physics vs 31 weeks in 2009

IS480

Charge radii of n-deficient Mg isotopes at COLLAPS

HFS structure of 21Mg observed in beta-decay asymmetry

Now differences in Mg charge radii known all across sd shell for 21-32Mg

D. Yordanov

IS501: Mossbauer studies

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.

-6-4-20246

Velocity (mm/s)

Rel

ativ

e em

issi

on (

arb.

uni

ts)

95 K

300 K

711 K

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

Sn4+

Sn2+

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.

K. Johnston et al.

IS430

Excitation spectra from particles

Gamma spectra

d(11Be,p)12Be d(11Be,d)11Be d(11Be,t)10Be

0+

2+

1-

1/2-

0+

2+

2+

1-

0+

2-

2+->0+

1-->0+

1/2+->1/2-

0+->2+

2+->0+

1-->2+

K. Riisager, J. Johansen

Most intense 11Be beam (for 10 days) behind REX used with T-REX setup

Mn for SSP

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 sitesInterstitial vs. substitutional fractions controls TC

General belief: Low thermal stability of interstitial Mn(~200 ºC with activation energy of 0.7 eV)

Direct identification of the Mn interstitial siteEvidence of high thermal stability of interstitial MnPossible implications on the strategies and prospects to increase TC in Mn-doped GaAs

56Mn in GaAs (s.i., n+ and p+)

56Mn in Ga1-xMnxAs (MBE grown with stable 55Mn)

L. Pereira, G. Correia

IS475224Ra Coulomb excitation

~105 ions/s at target, REX efficiency ~1%, q=52+ for Ra

2+ → 0+

X-rays

4+ → 2+

6+ → 4+

3- → 2+

7-→ 5-

8+ → 6+

1- → 0+

5- → 4+

L. Gaffney and P. Butler

IS499

44Ar at T-REX: CO2 and Kr contamination not a problemNew states identifiedVery 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 - IS488199Hg 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)

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

YO CP target for 1st REX-ISOLDE run: 9C yield dropped quickly after start – run not successful – need target tests

Miniball run on 72Kr from YO CP target: 10-fold yield drop within a few days, strong 72Ge contamin.

WITCH run on Ta W target: Very contaminated rare-earth beam, but some recoil spectra (on mixed beam) could be recorded

ZrO target with RILIS for Ga at COLLAPS: Target broken right before on-line run – cancelled

Main problems in 2010 (I)Main problems in 2010 (I)

GPS HRS

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 .

220Rn Miniball run: cancelled due to target failure during 202Rn run

202Rn Miniball run: target broke in the middle of the run; only partial statistics collected

96Kr Minball run with UC CP target: many contaminants and weak Kr signal at Miniball but 96Kr E(2+) observed in 2009 confirmed

Main problems in 2010 (II)Main problems in 2010 (II)

GPS HRS

Pb HP target for SSP collections: GLM deflection plates blocked (broken pinion); no beam for users

30Na from UC W target to Miniball: measured yield and counts at Miniball much below database value. Beam given to next user.

Tests of high-density UC target: GPS turbo fans go off. Pumps will probably survive only 3-4 days.

N-rich rare earths at ISOLTRAP (Ta W): no beam of interest found among stronger contamination. Another new mass measured.

Mn beam for Mossbauer studies (UC Ta): GPS HV trips above 30kV (requested HV>50kV). Extraction electrode exchanged and 40kV allowed very good results.

Main problems in 2010 (III)Main problems in 2010 (III)

GPS HRS

70-72Kr from YO CP target for ISOLTRAP: No beams visible among large Cl contamin. but more tests with multireflection isobar separator

Accelerator schedule 2011 (draft)Accelerator schedule 2011 (draft)

protons to ISOLDE April 25physics start ISOLDE May 2protons stop November 20(i.e. 29 weeks for physics vs 29.5 in 2010)

Several 24h injector stops every 6 weeks.Several long periods of machine developmentpartly with parasitic beam to ISOLDE (not guaranteed)

Shutdown period used for new GPS front-end

ISOLDE dates (still prelimin.)

Long CERN-wide shutdownLong CERN-wide shutdown

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

One year shutdown of CERN accelerator complex (to save money and manpower) planned for 2012

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