observation of non-exponential orbital electron-capture decay erice, september 16 - 24, 2009 fritz...
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Observation of non-exponential orbital electron-capture decay
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
FRS
1 Measurement of EC of stored H-like ions
Productiontarget
StorageRingESR
Heavy-IonSynchrotron
SIS
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
FFT
am plificationsum m ation
time
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
5
1 0
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
0
5
10
0
5
10
0
5
10
Frequency / kHz
Inte
nsity
/ ar
b. u
nits
201 84+
194 81+Tl
182 76+Pt182 76+
182 76+
189 79+
Ir
O s
Po
Hg
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
Pb
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
Hg
196 81+
204 84+
Pt
Pb
Pt Ir186 77+
Po
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
A q+X
15
0m
,g
6
5+
Dy
150
65
+
Tb
143
6
2+
143
m,g
6
2+
Eu S
m
157
68+
Er
127
55+
Cs
157
6
8+T
m
173
7
5+
166
72
+1
66
72+
180
78
+P
t
Re
Hf
Ta
152
6
6+
152
6
6+
Ho
Dy
159
6
9+
159
6
9+
13
6
59+
Tm
Yb
Pr
W
164
71+
171
74
Lu
16
4
71+
Hf
14
5
6
3+
122
53+
Gd
I
175
7
6+
161
70
+
138
6
0+161
70
+
16
8
7
3+16
8
73+
Os
TaW
Yb
Nd
Lu
14
9
65+
Tb
156
68
+
156
6
8+
Er
Tm
154
67+
154
67+
HoEr
163
71+
147
64
+
14
7
6
4+
147
6
4+
Dy
Tb
Gd
Lu
165
72
+1
65
7
2+
17
2
7
5+
163
7
1+
170
74
+
Hf
TaRe
W
Hf
10000 20000 30000 40000 50000 60000 70000 80000 90000 100000
8
7
6
5
4
3
2
1
0
Frequency / H z
Inte
nsity
/ ar
b. u
nits
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
Am
plit
ud
e
Am
plit
ud
e
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
β+
EC
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
a ve
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 -
11 eV
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
eV2
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 )