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bn angular correlations

bn angular correlations. LPC-Team : G. Ban, G. Darius, P. Delahaye, D. Durand, X. Flechard, M. Herbane, M. Labalme, E. Liénard , F. Mauger, A. Mery, O. Naviliat, D. Rodriguez. a. a. Allowed transitions, unpolarized nuclei. J.D. Jackson, PR106(1957) & NP4(1957).

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bn angular correlations

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  1. bn angular correlations LPC-Team : G. Ban, G. Darius, P. Delahaye, D. Durand, X. Flechard, M. Herbane, M. Labalme, E. Liénard, F. Mauger, A. Mery, O. Naviliat, D. Rodriguez

  2. a a Allowed transitions, unpolarized nuclei J.D. Jackson, PR106(1957) & NP4(1957) e – n angular correlation Fiertz interference SM S_/T_Interaction aF (CV,CS ) +1 -1 SM V – A theory |Ci|= |C’i| real Pure Fermi decay aGT (CA ,CT ) -1/3 +1/3 Pure G-T decay Deviations New Physics beyond the Standard Model

  3. pr (MeV/c) 6He Te (MeV) 46V f q Any observable linked to (q) will be sensitive to a Recoil ion momentum aGT = -1/3 q = 0° aF = +1 q = 180°

  4. r = CA MGT /CV MF x = 1/(1 + r²) 6He 32Ar Most precise measurements pure Fermi or G-T transitions a ~ aSM (1-a) F : aSM = 1 a = (|CS|²+|CS’|²)/CV² GT : aSM = -1/3 a = (|CT|²+|CT’|²)/CA²

  5. 6He 6Li + b- + ne (0+) GT (1+) 32Ar 32Cl* + b+ + ne (O+) F (O+) 31S + p (3.35 MeV) C £ T C 0 . 13 S £ 0 . 08 C A C V Present limits aGT = 0.3343 ± 0.0030 (1 s) C.H. Johnson, PR 132 (1963) 1149 Method : Analysis of the recoil energy spectrum aF = 0.9989± 0.0065 (1 s) E.G. Adelberger, P.R.L. 83 (1999) 1299 Method : Analysis of the energy spread of the delayed protons

  6. SPIRAL BEAMS http://www.ganil.fr/operation/available_beams/radioactive_beams.htm

  7. 6He • Pure GT transition • 100% G.S. to G.S. • T1/2 = 806.7 ms • Qb = 3.51 MeV, Tmax = 1.4 keV • High production rate : 3.8 108 ions/s Goal : improvement of Johnson 1963 experiment build the kinematics event/event adapted environment : Paul trap b - recoil ion coincidences measurements

  8. 3 4 1 2 Paul trap • no magnetic field • ions « at rest » in vacuum • ions well localized • open geometry : high detection solid angle

  9. Ty2 Tx2 Plastic + PSD Si mCP + Delay line anode j e- Tx1 Ty1 ion Position and Time of flight Position and Energy Injection Coincidences measurement back-to-backgeometry

  10. Production • SPIRAL: 3.8 108 ions/s • Efficiencies • RFQ cooler buncher : 20% • Paul trap : 10% • Efficiency of the detection setup : 2.8 ‰ • Cycle efficiency: 3.3 ‰ (100ms – limit of 105 ions per cycle into the RFQ cooler buncher) • Radioactive decay: 86% One week of data taking First experiment @ LIRAT accepted by the PAC 107 coincident events to get sa/a = 5 ‰

  11. 8He • Pure GT transition, 84 % • Eg = 980.8 keV, t = 8 fs • T1/2 = 119 ms • Qb = 9.67 MeV, Tmax = 6.9 keV • Production rate : 3.5 105 ions/s Doppler shift of g energy linked to 8Li recoil motion 18Ne V. Egorov, NPA621(1997)745 • Pure F transition, 7.7 % • Eg = 1041.55 keV, t = 1.8 fs • T1/2 = 1672 ms • Qb = 2.38 MeV, Tmax = 0.24 keV • aF = 1.06 ± 0.19 (2s) [5.3 103 events]

  12. z 18Ne V. Vorobel, EPJA16(2003)139 aF =+1 < dE >(0°,180°) = Eg ( < Rz> / Mionc) 2< dE > (eV) aF =-1 + - Te (MeV) Doppler shift measurement 2< dE > = 2Eg (< Rz> / Mionc)

  13. 8He Qb = 9.67 MeV Tmax = 6.9 keV Eg = 980.8 keV t = 8fs aGT =+1/3 Qb = 2.38 MeV Tmax = 0.24 keV Eg = 1041.55 keV t = 1.8fs 2< dE > (eV) aGT =-1/3 18Ne enhanced sensitivity ! Te (MeV) t= 8fs l = 33 ÅDT ~ 400 eV in Carbon j e- HPGe g Paul trap Injection 8He vs 18Ne

  14. measurement of p energy shift instead of broadening 32Ar • Pure F transition, 23 % • T1/2 = 98 ms • Ep = 3.35 MeV, G = 20 eV • Qb = 5.1 MeV, Tmax = 0.52 keV • Production rate : 1.6 103 ions/s Goal : improvement of ISOLDE 1999 experiment less sensitive to 32Ar mass (~ factor 5) b - p coincidences measurements

  15. p kinematic shift • feasability tests performed in 2000 @ SIRa • experiment accepted in 2001 @ GANIL, • identification station • (coll.: Argonne, Dubna, Louvain-la-Neuve, Leuven) • unfortunately not still scheduled … • 300 32Ar/s, clean beam • ions implanted in carbon foil • p & b detected by Si telescopes

  16. welcome new measurement with alternative method ! aF ~ 1.00 ± 0.06 (1s) Mexp( 32Ar) = -2180 ±50 keV : MIMME( 32Ar) = -2209.3 ±3.2 keV : aF = 0.9989 ± 0.0065 (1s) • end 2001 : precise measurement @ ISOLTRAP of 32Ar mass K. Blaum, PRL91(2003) real new challenge …. Mexp( 32Ar) = -2200.2 ±1.8 keV Consistent with MIMME, lower uncertainty …! • a few 105 events in p peak need to get Da = 0.006 (1s) • clean beam with good emittance is needed • experiment could be performed @ LIRAT with RFQ in continuous mode 32Ar ISOLDE experiment results : some key stages… • performed in 1999 E.G. Adelberger, PRL83(1999)

  17. r = CA MGT /CV MF r2~(ft)-1 & t = T1/2(1 + GEC)/BR … or precise a spectroscopic information • 33Ar : mixed transition B(GT)/B(F) amixed = 0.944 ± 0.004 B(GT)/B(F) = 0.044 ± 0.002 Connected experiments – spectroscopic information • 32Ar : precise mass measurement • 21Na : precise branching ratio measurement precise a …. amixed = 0.5243 ± 0.0092 (3.6s from SM) N.D. Scielzo, PhD Thesis, Berkeley (2003) A. Garcia, hyp.Int.129(2000) (Shell-model : 0.055…) (not more valid …!)

  18. Conclusions • bn angular correlations measurement : still an up-to-date subject • LIRAT-SPIRAL : place of high exotic beam production & some exotic noble gazes are the present best candidates for bn angular correlations measurements constraints on exotic weak couplings could be improved @ LIRAT • Experiments sometimes linked to reliable spectroscopic data

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