1 Fundamental symmetries studies with electron spectroscopy at FRIB l t t t FRIB • Chi Chirality flipping interactions lit fli i i t ti • Axial and tensor • Fermi and scalar • Tools: R × B spectrometer p Cyclotron Radiation Emission Spectroscopy • Examples of other uses of beta spectroscopy: Nuclear structure for 2 decays Nuclear structure for 2 decays • • • Efficiency of some neutrino detectors Alejandro Garcia University of Washington Fundamental symmetries at FRIB
2 0 + Fundamental symmetries studies with 6 He 6 He Q ~3.5 MeV 1 + • Simple decay (~100% to ground state) • Pure Gamow ‐ Teller decay 6 Li • Half ‐ life ~1 sec → appropriate for trapping pp p pp g • Large Q ‐ value → good for seeing effects of n Compare to neutron: • Noble gas → no worries about chemistry No backgrounds from neutron captures • • Light nucleus → ab ‐ initio calculations • Pure GT transition (simpler decay, no polarization) 6He “little b ” 6He “little a ” P. Muller, A. Leredde Argonne National Lab P. Muller, A. Leredde Argonne National Lab A. Knecht, PSI, Switzerland X. Fléchard, E. Liennard, LPC, CAEN, France A. Hime, B. Vandebender, PNNL, O. Naviliat-Cuncic, NSCL, MSU Y. Bagdasarova, A. Garcia, D. Hertzog, R. Hong, P. Y. Bagdasarova, A. Garcia, D. Hertzog, R. Hong, P. A. Knecht, PSI, Switzerland A Knecht PSI Switzerland Kammel, J. Kofron, G. Rybka, M. Sternberg, Y. Bagdasarova, A. Garcia, R. Hong, M. Sternberg, D. D. Storm, H.E. Swanson, F. Wauters, D. Storm, H.E. Swanson, F. Wauters, D. Zumwalt Zumwalt University of Washington University of Washington Fundamental symmetries at FRIB
3 Now ~10 10 atoms of 6 He/s at Seattle via 7 Li(d 3 He) 6 He Now 10 atoms of He/s at Seattle via Li(d, He) He Most intense source of 6He in the world here at CENPA. A. Knecht et al. A K ht t l Typical decay density is about NIM A. 660 , 43 10 9 decays/s cm 3 … (2011) (Good neutron decay density is1 decay/s cm 3 ) 3 ) i 1 d / Fundamental symmetries at FRIB
6 He lifetime, ab-initio calculations, g A (nuclear) 4 2 2 2 1 1 G G V V ˆ 2 f ˆ F ud With calculated and lifetime can extract g A g f O i O i A f ( E ) t K Several `ab initio’ calculations show agreement on matrix element at the Several ab-initio calculations show agreement on matrix element at the few percent level: Schiavilla & Wiringa PRC 65 , 054302 (2002) Navratil & Ormand, PRC 68 , 034305 (2003) Previn et al., PRC 76 , 064319 (2007) Vaintraub et al., PRC 79 , 065501 (2009) But experimental situation was unclear. Fundamental symmetries at FRIB
Knecht et al. , Phys. Rev. Lett. 108 , 122502 (2012); 6 He lifetime, ab-initio calculations, g A (nuclear) 5 Phys. Rev. C 86 , 035506 (2012). • We resolved the discrepancy. Our result in combination with ab ‐ initio calculations shows that extraneous quenching l l ti h th t t hi is at most about 2%. Now limited by theoretical uncertainty. Fundamental symmetries at FRIB
Searches for Tensor currents. 6 Are nuclear weak decays Or chirality-flipping interactions? carried only by W’s? e+ d e+ d e e+ e+ e d e Lepto-Quark ? u u e+ u W L L H 2 C e f 5 5 i A e L R ' R ' L Finding these would be a ( C C ) e ( C C ) e f i T T e T T e big deal Decay rate: ' Re 2 C C C A T T b 2 2 2 2 2 2 ' 2 C C C A T T p p m e e dw dw 1 a b 0 2 2 2 E E E ' 2 C C C 1 e e A T T a 2 2 2 2 2 2 3 3 ' 2 C C C A T T Fundamental symmetries at FRIB
6He “ little a ” 7 P. Muller, A. Leredde Argonne National Lab Electron and 6 Li detected in coincidence Electron and 6 Li detected in coincidence • • E ‐ E scintillator system for electron (energy, X. Fléchard, E. Liennard, LPC, CAEN, France • start of time ‐ of ‐ flight) O. Naviliat-Cuncic, NSCL, MSU Micro ‐ channel plate for 6 Li (position, TOF) • A Knecht PSI S it erland A. Knecht, PSI, Switzerland Y. Bagdasarova, A. Garcia, R. Hong, M. Sternberg, D. Storm, H.E. Swanson, F. Wauters, D. Zumwalt University of Washington Fundamental symmetries at FRIB
Magneto ‐ Optical Trap 8 • RF discharge in xenon/krypton to excite into metastable state • Cycling on 1083 nm transition to slow down and magneto ‐ optically trap • Based on experience from 6 He, 8 He charge radius measurements by ANL h di t b ANL collaborators: L. ‐ B. Wang et al., PRL 93 , 142501 (2004) P M P. Mueller et al., PRL 99 , 252501 ll l PRL 99 252501 (2007) Fundamental symmetries at FRIB
9 Precision beta decay versus others: Can “precision” compete with “energy”? Yes Can precision compete with energy ? Yes. F. Wauters et al. PRC 89 , 025501 (2014) Fundamental symmetries at FRIB
Is it possible to break the “ b ~ 10 -3 barrier” Detect little b 10 and reach into really interesting terrain? p p m e e dw dw 1 a b 0 E E E e e quadratic linear 2 2 2 ' 2 2 C C C C C C 1 1 A T T a 2 2 2 3 ' 2 C C C A T T ' Re 2 C C C A T T b b 2 2 2 2 2 2 ' 2 C C C A T T 200 keV E thres Can get stats with rates of about 10 4 Hz. b 10 / N Fundamental symmetries at FRIB
Typical beta spectrometers work best with a Detect little b 11 `point’ source From Knutson et al. submitted to PRC (Recent work on the shape of the beta shape of the beta spectrum of 14O.) Hard to apply this technique for 6He: Hard to apply this technique for 6He: presently we can load only ~1000 atoms in laser trap Fundamental symmetries at FRIB
R × B spectrometer for 6He (similar to idea being pursued by PERC): 12 2 sin 2 cos R B 2 D R ( p ) max cos R B ( pc / MeV ) 1 3 ( B / Tesla ) Existing device at PSI 100 kV platform Fundamental symmetries at FRIB
13 Comparison of neutron to 6He shape measurement with R × B spectrometer Parameter Neutron 6He (PERC) (CENPA) K eMax (MeV) 0.97 3.5 B3 (Tesla) 0.15 0.15 10 6 10 5 Effective decay rate (1/s) T Trappable bl N No Y Yes Image size at p ≈ 0 1×1 cm2 0.3×0.3 cm2 Systematic uncertainties: • Singles measurement: backgrounds? Looks ok. • • Effects from unobserved backscattering? Looks ok Effects from unobserved backscattering? Looks ok. • Non-trapped 6He? Looks manageable. • Trajectories in realistic configuration: any surprises? Needs more study Fundamental symmetries at FRIB
6 He “little b ”: Project 8 collaboration is aiming at detecting electrons from 3H decay. 14 P8 idea: Pick up cyclotron radiation •None of the usual problems of calorimetry: scattering, dead layers, low resolution, etc… •Good linearity between cyclotron frequency and energy. •Excellent resolution Fundamental symmetries at FRIB
6 He “little b ”: Project 8 collaboration is aiming at detecting electrons from 3H decay. 15 P8 idea: Pick up cyclotron radiation Project 8 recently showed impressive results from a conversion electron source lt f i l t (Asner et al. arXiv:1408.5362) Fundamental symmetries at FRIB
6 He “little b ”: aiming for 10 -4 with Project-8 like system 16 Intense production at CENPA (decay density up to about 10 9 decays/s cm 3 !) Pick up cyclotron and 6 He as gas make it well suited for radiation P8-like approach. pp Need larger guide (58x29 mm 2 vs. 11x4 mm 2 ) --loose power prop to area P 1 / A 1 / 40 2 2 --but compensate due to higher energies P 1 B --many alternative schemes to be considered many alternative schemes to be considered Next: test with conversion lines at energies closer to 6He Isotope sotope Decay ecay t 1/2 (days) t 1/2 (days) Ee (keV) e ( e ) 131mXe IT 12 129,158,163 133mXe IT 2.2 233 ‐ 133Xe 5.3 346 Fundamental symmetries at FRIB
6 He “little b ”: aiming for 10 -4 with Project-8 like system 17 Fundamental symmetries at FRIB
6 He at CENPA summary: 18 Present and near future work (little a): • Several ongoing upgrades. Expect trapping about 1000 atoms with little bkgd. • Determination of apparatus parameters: E field, geometry, efficiencies, instabilities. Present and near future work (little b): • Test “Project8-like” setup with higher energy conversion sources. • Put together similar system to detect betas in 200-900 keV range. • We would consider again the “ R × B Spectrometer” idea if the above fails. We would consider again the R B Spectrometer idea if the above fails. Goals 3 years: Goals 3 years: Determination of a to ~0.1%; R&D to determination of b. Determine b to ~10 -3 . Goals 6 years: Goals 6 years: Determine b to ~10 -4 . Fundamental symmetries at FRIB
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