Observation of non-exponential orbital electron-capture decay Erice, September , 2009 Fritz Bosch, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt
FRS - ESR Collaboration D. Atanasov, F. Bosch, D. Boutin, C. Brandau, L.Chen, Ch. Dimopoulou, H. Essel, Th. Faestermann, H. Geissel, E. Haettner, M. Hausmann, S. Hess, P. Kienle, Ch. Kozhuharov, R. Knöbel, J. Kurcewicz, S.A. Litvinov, Yu.A. Litvinov, L. Maier, M. Mazzocco, F. Montes, A. Musumarra, G. Münzenberg, C. Nociforo, F. Nolden, T.Ohtsubo, A. Ozawa, W.R. Plass, A. Prochazka, R. Reuschl, Ch. Scheidenberger, D. Shubina, U. Spillmann, M. Steck, Th. Stöhlker, B. Sun, T.Suzuki, S. Torilov, H. Weick, M. Winkler, N. Winckler, D. Winters, T. Yamaguchi
1. Measurement of orbital electron-capture decay (EC) of stored and cooled H-like ions 2. Observation of non-exponential EC decays of stored H-like 140 Pr and 142 Pm ions Questions, hypotheses and objections 3. Preliminary data of EC decay of H-like 122 I ions Next steps Outline
Fragment Separator FRS 1 Measurement of EC of stored H-like ions Production target Storage Ring ESR Heavy-Ion Synchrotron SIS Linear Accelerator UNILAC
Production and Separation of Exotic Nuclei Highly-Charged Ions In-Flight separation Cocktail or mono-isotopic beams Hans Geißel
The ESR : E max = 420 MeV/u, 10 Tm, e -, stochastic, laser cooling B. Franzke, P. Kienle, Markus Steck, P. Beller †, F. Nolden, Ch. Dimopoulou
'Cooling': narrowing velocity, size and divergence enhancing phase space density momentum exchange with 'cold', collinear e- beam. The ions get the sharp velocity of the electrons, small size and divergence Electron cooling: G. Budker, 1967 Novosibirsk
Schottky Mass-and Lifetime Spectrometry (SMS) Continuous digitizing and storage of raw data
time SMS 4 particles with different m/q Yuri A. Litvinov GSI
Sin( 1 ) Sin( 2 ) Sin( 3 ) Sin( 4 ) 11 22 33 44 time Fast Fourier Transform SMS
Schottky frequency spectra Schottky frequency spectra Δαkl
Two-body orbital electron-capture decay of stored and cooled highly-charged ions
ESR: circumference ≈ 10 4 cm At mean distances below about 10 cm intra-beam scattering disappears For 1000 stored ions, the mean distance amounts to about 10 cm "Phase transition" to a linear ion-chain M. Steck et al., PRL 77, 3803 (1996)
Stochastic (3.5 s) + continuous electron cooling D. Boutin
Two-body beta decay
EC in Hydrogen-like Ions FRS-ESR Experiment EC (H-like) = (6) s -1 (decay of 140 Pr 58+ ) bare) = (8) s -1 (decay of 140 Pr 59+ ) (neutral) = (1) s -1 G.Audi et al., NPA729 (2003) 3 Expectations: EC (He-like) = (7) s -1 (decay of 140 Pr 57+ ) EC (H-like)/ EC (He-like) ≈ 0.5 EC (neutral atom) ≈ 1 EC (H-like)/ EC (He-like) = 1.49(8) Y.A. Litvinov et al., PRL, (2007) Y.A. Litvinov et al., PRL 99, (2007)
Measurement of EC of single stored H-like ions Sensitivity to single stored ions F. Bosch et al., Int. J. Mass Spectr. 251 (2006) 212 Recording the correlated changes of peak intensities of mother- and daughter ions defines the decay
Evaluation of amplitude distributions corresponding to 1,2,3-particles Amplitude Daughter Mother Why we have to restrict onto 3 injected ions at maximum ? The variance of the amplitude gets larger than the step 3→4 ions Nicolas Winckler
2 Observation of non-exponential EC of 140 Pr and 142 Pm
Examples of Measured Time-Frequency Traces Continuous observation Detection of ALL EC decays Delay between decay and "appearance" due to cooling Parent/daughter correlation Well-defined creation and decay time No third particle involved
140 Pr all runs: 2650 EC decays from 7102 injections Yu.A. Litvinov et al., Phys. Lett. B 664 (2008)
142 Pm: 2740 EC decays from 7011 injections
142 Pm: zoom on the first 33 s after injection
P.A. Vetter et al., Phys. Lett. B 670 (2008) 196 EC decay of implanted 142 Pm & 180 Re Th. Faestermann et al., Phys. Lett. B 672 (2009) 227 final state is not a true two-body state: neutrino, recoil and phonon of the lattice
β + decay of 1 or 2 stored H-like 142 Pm ions preliminary
EC decay of 1 or 2 stored H-like 142 Pm ions
FFT of EC- sc. β + - decay of 1 or 2 stored 142 Pm β+β+ EC
Synopsis ( 140 Pr & 142 Pm) M parent ω (1/s) Period lab (s) Amplitude φ (rad) (10) 7.06(8) 0.18(3) 0.4(4) (27) 7.10(22) 0.23(4) - 1.6(4)
2 Questions, hypotheses and objections
1. Are the periodic modulations real ? → artefacts are improbable, but statistical significance only 3.5 σ at present 3. How can coherence be preserved for a confined motion, stochastic interactions and at continuous observation? Straightforward Questions 2. If the data are not artefacts, we have to have macroscopic coherence times
µ = µ N (calc.) Coherent excitation of the 1s hyperfine states F = 1/2, F= 3/2 Beat period T = h/ΔE; for ΔE ≈ 1 eV → T ≈ s Decay can occur only from the F=1/2 (ground) state Periodic spin flip to "sterile" F=3/2 ? → λ EC reduced "Quantum Beats" from the Hyperfine States
1. Decay constants for H-like 140 Pr and 142 Pm should get smaller than expected. → NO 2. Statistical population in these states after t ≈ max [1/λ flip, 1/λ dec. ] 3. Phase matching over many days of beam time? Periodic transfer from F = 1/2 to "sterile" F = 3/2 ?
The observables in the GSI experiments 1. Mass M P and charge of parent ion 3. Time t a of daughter appearance 4. Not observed: 140 Pr: T R = 44 eV Delay: 900 (300) msec 142 Pm: T R = 90 eV Delay: 1400 (400) msec from observed frequencies: → p transformed to n (hadronic vertex) → bound e - annihilated (leptonic vertex) → ν created at t d as flavour eigenstate ν e supposing lepton number conservation 2. Mass M D of cooled daughter ion
"An essential feature of the GSI experiments is that the neutrino is not detected. Experiments which do not observe the neutrino cannot display interference" A. G. Cohen et al., hep-ph / and PLB Specific ν flavours are "detected" in all experiments by specific reaction products and by the constraints of energy-, momentum- and lepton number-conservation: W + + W - → μ + + ν μ + e - + ν e (bar) creation of neutrino flavour eigenstates states observed by missing momenta supposing lepton number conservation
Charged-Current event at SNO Absorption of a v e Appearance of two protons and of a fast electron: ν e - component picked-up from incoming neutrino, supposing lepton number conservation ν e + n → p + e - → The GSI experiments observe the creation of an electron-neutrino flavour eigenstate ν e at the origin on the same footing as any neutrino detector, via a precise time-resolved measurement of masses and charges
Energy and momentum conservation for a true two-body decay ΔE ν ≈ Δm 2 /2M P ≈ 3.1· eV Δp ν ≈ - Δm 2 /2 ≈ eV E, p = 0 (c.m.) M, p i 2 /2M ν e (m i, p i, E i ) M + p 1 2 /2M + E 1 = E M + p 2 2 /2M + E 2 = E "Asymptotic" conservation of E, p m 1 2 – m 2 2 = Δm 2 = 8 · eV 2 E 1 – E 2 = ΔE ν p 1 – p 2 = Δp ν if the frequency ω in cos(ωt + φ) = ΔΕ ν / ћ = Δm 2 /2M p → period T of modulation proportional to the mass of the parent ion
3 Preliminary data of EC decay of stored H-like 122 I ions Experiment:
Few (1..3) stored parents: inj., 1164 EC decays
Many parent ions ( ): 5718 injections ~ 4536 EC-decays
Few (1..3) parent ions: injections, 1164 EC decays preliminary
Few parent ions: Frequency spectrum (binning = 0.64 s) preliminary ● ● ● f = 0.17 Hz preliminary
Problems of data analysis for many parent ions 1. No correlations, only onset of daughter trace measured 2. Erraneous assignments possible (delayed cooling) 3. Amplitudes show large variance → automatized and several independent manuel evaluations needed computer analysis very difficult
Next steps To probe whether the modulations could be connected with the spin and/or the hyperfine structure of the H-like ions, we will investigate next the EC decay of He-like 142 Pm. To probe whether the scaling of the period with the nuclear mass could be connected with the magnetic rigidity, we will perform experiments with the same ion type but at different velocities Most important: significant improvement of Schottky detector! Independent verification or disprove at other facilities is needed (CSRe ring at IMP/Lanzhou; WITCH setup at ISOLDE/CERN )