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Bentley et al - Istanbul May 7th 20101 Letter of Intent: Letter of Intent: Isospin Symmetry and Transition Rates in Isobaric Multiplets M.A.Bentley,

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Presentation on theme: "Bentley et al - Istanbul May 7th 20101 Letter of Intent: Letter of Intent: Isospin Symmetry and Transition Rates in Isobaric Multiplets M.A.Bentley,"— Presentation transcript:

1 Bentley et al - Istanbul May 7th 20101 Letter of Intent: AGATA@GSI Letter of Intent: Isospin Symmetry and Transition Rates in Isobaric Multiplets M.A.Bentley, R.Wadsworth et al (Univ.York) D.Rudolph et al (Lund) A.M.Bruce et al (Brighton) P.Reiter et al (Koln) S.Lenzi et al (Padova) G.deAngelis, E.Sahin et al (INFN) A.Obertelli et al (CEA Saclay) M.Labiche, J.Simpson (STFC Daresbury Lab.) + PRESPEC TEAM (GSI)

2 Bentley et al - Istanbul May 7th 20102 AIMS Topic: Isospin dependence of B(E2) strengths in T=1 triplets... Aims: To test a direct prediction (largely untested) of isospin formalism: dependence of B(E2) with T z for IAS transitions To search for isospin mixing effects at the ~ few % level Examine precision lifetime measurements of T=1 2 + to 0 + transtions in T=1 Triplet Assume no isospin mixing (hence T=1 to T=1 transitions only) IS IV

3 Bentley et al - Istanbul May 7th 20103 LINEAR DEPENDENCE of ME with Tz PRESPEC Meeting: S363 Report3 et al...

4 Bentley et al - Istanbul May 7th 20104 Effect of Isospin Mixing Effect of isospin mixing on B(E2) strengths in T=1 triplets...?? Proximity of T=1 and T=0 states in odd-odd N=Z system T=0 admixtures possible in both 0 + and 2 + states Introduces isovector components in B(E2) in N=Z odd- odd (T z =0)

5 Bentley et al - Istanbul May 7th 20105 AIMS Perform high-precision RELATIVE measurement of B(E2) in T=1 TRIPLET Use identical method for B(E2) measurement Use identical population method for states of interest Try to eliminate direct/side feeding Use identical experimental conditions PERFORM in same EXPERIMENT TWO POSSIBLE CASES... A=46 T=1 triplet A=62 T=1 triplet

6 Bentley et al - Istanbul May 7th 20106 A=46 Isobaric Triplet 46 Cr - P.J.Garrett et al Phys. Rev. Lett. 87(2001)132502 B(E2)’s known only at ± 20% level T 1/2 = 8-9 ps

7 Bentley et al - Istanbul May 7th 20107 46 Cr Stack of 3 gold foils (~500 mg/cm 2 ) separated by ~1mm (Sort of) differential plunger Designed for specific case/lifetime Key points: 2 + states all populated directly by Coulex Lifetime determined from lineshape alone Can use 2,3,4 foils... Could use Koln plunger... Proposed Method

8 Preliminary Simulation 15.9 degrees 36.0 degrees Performed for “Euroball” RISING Assumes 2% energy resolution 10,000 counts in triple-peak 2x750mg/cm 2 + 1x500mg/cm 2 1mm gap 915 keV transition in 46 V 150Mev/u ±20% in B(E2)

9 RATES Make 46 Cr, 46 V and 46 Ti from fragmentation of 78 Kr or 58 Ni primary beam Assume 1x10 10 pps 78 Kr, 4g/cm 2 primary Be target Assume FRS transmission efficiency of 20% (LISE) 3% efficiency in a ring with 2% energy resolution 450mb Coulex cross section (measured) 50kHz secondary beam limit 2000 mg/cm 2 Au in total... GIVES: 1.5kHz 46 Cr → 25,000 counts in line-shape in 3 days 50kHz 46 V → 100,000 counts in line-shape in 1 day 50kHz 46 Ti → 100,000 counts in line-shape in 1 day

10 D.Rudolph et al N=Z N=Z+2 A=62 Isobaric Triplet

11 D.Rudolph et al 62 Ge: 2 + state only tentatively assigned – needs confirmation 62 Ga: 2 + state only tentatively assigned – needs confirmation 62 Ge: 2 + state is non-YRAST – Coulex ideal to populate state Key points: Isospin-mixing predicted to increase with Z 2 Confirmation of 2 + states in 62 Ga and 62 Ge Shorter half-life (~3 ps) Not as high-statistics as A=46, but larger effect?

12 RATES Make 62 Ge, 62 Ga and 62 Zn from fragmentation of 78 Kr primary beam Assume 1x10 10 pps 78 Kr, 4g/cm 2 primary Be target Assume FRS transmission efficiency of 20% (LISE) 3% efficiency in a ring with 2% energy resolution 450mb Coulex cross section (assumed same as A=46) 50kHz secondary beam limit 2000 mg/cm 2 Au in total... GET: 1.5kHz 62 Ge → 1,000 counts in line-shape in 3 days 50kHz 62 Ga → >100,000 counts in line-shape in 1 day 50kHz 62 Zn → >100,000 counts in line-shape in 1 day

13 UNIQUENESS? Key Points: 1.Technique requires high-energy / high β Allows thick targets, large gaps, short lifetimes Gives more pronounced line-shape 2.Position-resolution of AGATA benefits technique (improves line-shape, allows for definition of effective “rings”) BOTH give major advantage over MSU capability (for example)


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