Observation of non-exponential orbital electron-capture decay

transcript

Erice, September 16 - 24, 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 140Pr and 142Pm ions

Questions, hypotheses and objections

3. Preliminary data of EC decay of H-like 122I ionsNext steps

Outline

Fragment Separator

1 Measurement of EC of stored H-like ions

Productiontarget

StorageRingESR

Heavy-IonSynchrotron

LinearAccelerator

UNILAC

Production and Separation of Exotic Nuclei

Highly-Charged IonsIn-Flight separation

Cocktail or mono-isotopic beams

Hans Geißel

The ESR : Emax = 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 exchangewith 'cold', collinear e- beam. The

ionsget the sharp velocity of the

electrons,small size and divergence

Electron cooling: G. Budker, 1967 Novosibirsk

Electron cooler

G as-target

Q uadrupole-trip let

Septum -m agnet

D ipole m agnet

Fast kickerm agnet

RF-Acceleratingcavity

Hexapole-m agnets

From the FR S

Extraction

To the S IS

Q uadrupole-dublet

Schottky p ick-ups

Schottky Mass-and Lifetime Spectrometry (SMS)

Continuous digitizing and storage of raw data

SchottkyP ick-ups

Stored ion beam

f ~ 2 M H z0

am plificationsum m ation

SMSSMS

4 particles with different m/q

Yuri A. Litvinov GSI

Sin(1)

Sin(2)

Sin(3)

Sin(4)

1234time

Fast Fourier Transform

SMSSMS

0 1 0 . 0 2 0 . 0 3 0 . 0 4 0 . 0 5 0 . 0 6 0 . 0 7 0 . 0 8 0 . 00

8 0 . 0 9 0 . 0 1 0 0 . 0 1 1 0 . 0 1 2 0 . 0 1 3 0 . 0 1 4 0 . 0 1 5 0 . 0 1 6 0 . 0

1 6 0 . 0 1 7 0 . 0 1 8 0 . 0 1 9 0 . 0 2 0 0 . 0 2 1 0 . 0 2 2 0 . 0 2 3 0 . 0 2 4 0 . 0

240.0 250.0 260.0 270.0 280.0 290.0 300.0 310.0 320.0

know n m asses A q+X unknow n m asses

N um ber of channels 216

R ecord ing tim e 30 sec

188 78+Pt

Frequency / kHz

201 84+

194 81+Tl

182 76+Pt182 76+

182 76+

189 79+

189 79+Au

177 74+W

196 82+Bi

196 82+Pb

184 77+Pt

184 77+Ir198 83+Bi

191 80+Tl

191 80+Hg

194 81+Au

200 83+Bi

183 76+Ir

183 76+O s

195 81+Tl195 81+PbPb

188 78+ 178 74+Re

190 79+Au

197 82+Bi

197 82+Pb

185 77+Ir

185 77+Pt192 80+Tl

192 80+Hg

199 83+Bi187 78+Pt

187 78+Au

190 79+Hg

IrAu 181 75+

198 82+Pb

193 80+Tl

193 80+Hg

194 80+Tl194 80+

189 78+

Tl191 79+Hg

187 77+

199 82+ Pb

196 81+

204 84+

Pt Ir186 77+

187 77+Au

BiPbPb

182 75+Ir

194 80+Hg 189 78+Au189 78+

201 83+Po

201 83+Bi184 76+

184 76+O s

191 79+Au

203 84+Po

186 77+Pt

186 77+Ir181 75+R e198 82+Bi

193 80+Pb199 82+

O s181 75+

200 82+Bi

195 80+Tl

197 81+Pb

197 81+Bi 192 79+Hg

192 79+Au

198 81+Bi

198 81+Pb193 79+Tl

193 79+Hg

188 77+Au 205 84+Po

200 82+Pb200 82+Po195 80+Pb

190 78+Hg

190 78+Au

185 76+Pt

202 83+Po

202 83+Bi 197 81+Tl198 81+Pb

188 77+Pt

10000 20000 30000 40000 50000 60000 70000 80000 90000 100000

Frequency / H z

m ass know n m ass unknow n

Schottky frequency spectraSchottky frequency spectra

Δαkl

Two-body orbital electron-capture decay of stored and cooled highly-charged ions

ESR: circumference ≈ 104 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) = 0.00219(6) s-1 (decay of 140Pr58+)

bare) = 0.00158(8) s-1 (decay of 140Pr59+)

(neutral)= 0.00341(1) s-1 G.Audi et al., NPA729 (2003) 3

Expectations:

EC(He-like) = 0.00147(7) s-1 (decay of 140Pr57+)

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 Y.A. Litvinov et al., PRL 99, 262501 , 262501

(2007)(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

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 140Pr and 142Pm

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

140Pr all runs: 2650 EC decays from 7102 injections

Yu.A. Litvinov et al., Phys. Lett. B 664 (2008) 162-168

142Pm: 2740 EC decays from 7011 injections

142Pm: zoom on the first 33 s after injection

P.A. Vetter et al., Phys. Lett. B 670 (2008) 196

EC decay of implanted 142Pm &180Re

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 142Pm ions

preliminary

EC decay of 1 or 2 stored H-like 142Pm ions

FFT of EC- sc. β+- decay of 1 or 2 stored 142Pm

Synopsis (140Pr & 142Pm)

Mparent ω(1/s) Periodlab (s) Amplitude φ(rad)

140 0.890(10) 7.06(8) 0.18(3) 0.4(4)

142 0.885(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 = +2.7812 µN (calc.)

Coherent excitation of the 1s hyperfine states F = 1/2, F= 3/2 Beat period T = h/ΔE; for ΔE ≈ 1 eV → T ≈ 10-15 s

Decay can occur only from the F=1/2 (ground) state Periodic spin flip to "sterile" F=3/2 ? → λEC reduced

"Quantum Beats" from the Hyperfine States

1. Decay constants for H-like 140Pr and 142Pm should

get smaller than expected. → NO

2. Statistical population in these states after

t ≈ max [1/λflip, 1/λdec.]

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 MP and charge of parent ion

3. Time ta of daughter appearance4. Not observed:

140Pr: TR = 44 eV Delay: 900 (300) msec

142Pm: TR = 90 eV Delay: 1400 (400) msec

from observed frequencies: → p transformed to n (hadronic vertex) → bound e- annihilated (leptonic vertex) → ν created at td as flavour eigenstate νe supposing lepton number conservation

2. Mass MD 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 / 0810.4602 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+ + νμ + e- + νe(bar)

creation of neutrino flavour eigenstatesstates observed by missing momentasupposing lepton number conservation

Charged-Current event at SNO Absorption of

Appearance of two protons and of a fast electron:

νe- component picked-up from incoming neutrino, supposing lepton number conservation

νe + n → p + e-

→ The GSI experiments observe the creation of an electron-neutrino flavour eigenstate νe at the origin

on the samefooting as any neutrino detector,

viaa precise time-resolved

measurementof masses and charges

Energy and momentum conservation for a true two-body decay

ΔEν ≈ Δm2/2MP ≈ 3.1·10-16 eV Δpν ≈ - Δm2/2< Eν > ≈ - 10 -

E, p = 0 (c.m.)

M, pi2/2M

νe (mi, pi, Ei)M + p1

2/2M + E1 = E M + p2

2/2M + E2 = E"Asymptotic" conservation of E, p

m12 – m2

2 = Δm2 = 8 · 10-5

E1 – E2 = ΔEν

p1 – p2 = Δpν

if the frequency ω in cos(ωt + φ) = ΔΕν / ћ = Δm2/2Mp → period T of modulation proportional to the mass of the

parent ion

3 Preliminary data of EC decay of stored H-like 122I ions

Experiment: 31.07.2008-18.08.2008

Few (1..3) stored parents: 10 808 inj., 1164 EC decays

Many parent ions (15...30): 5718 injections ~ 4536 EC-decays

Few (1..3) parent ions:10 808 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 142Pm.

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 )

Observation of non-exponential orbital electron-capture decay

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