Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere
description
Transcript of Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere
• physics of 0+ → 0+ transitions
• recent experimental efforts
• world data on 0+ → 0+ decay
• future studies
Bertram Blank, CEN Bordeaux-Gradignan ISOLDE WS, 12-14 february 2007
• SM is theory which describes electro-weak interaction• BUT: parameters have to be determined experimentally
e.g. masses, coupling constants, mixing angles, etc.• nuclear decay is weak process and may allow for
determination of these parameters• 5 different couplings possible due to Lorentz invariance:
- scalar coupling (S)
- vector coupling (V)
- tensor coupling (T)
- axial-vector coupling (A)
- pseudo-scalar coupling (P)• decay: mainly vector and axial-vector V-A theory• weak contribution from other coupling?? scalar, tensor coupling• determination of vector coupling constant: 0+ 0+, n decay, decay• determination of axial-vector coupling constant: neutron decay
• SM is theory which describes electro-weak interaction• BUT: parameters have to be determined experimentally
e.g. masses, coupling constants, mixing angles, etc.• nuclear decay is weak process and may allow for
determination of these parameters• 5 different couplings possible due to Lorentz invariance:
- scalar coupling (S)
- vector coupling (V)
- tensor coupling (T)
- axial-vector coupling (A)
- pseudo-scalar coupling (P)• decay: mainly vector and axial-vector V-A theory• weak contribution from other coupling?? scalar, tensor coupling• determination of vector coupling constant: 0+ 0+, n decay, decay• determination of axial-vector coupling constant: neutron decay
2F
2V Mg
Kft
2GT
2A Mg+
• in general:
• for 0+ 0+ transitions: only vector current due to selection rules
• experimental quantities: masses of parent and daughter, half-life, branching ratio
• K / (hc)6 = 8120.271(12) * 10-10 GeV-4 s = constant, <MF>2 = T(T+1) - TziTzf
• gv can be determined, Vud = gv / gF, quark-mixing matrix element
• one high-precision measurement would be enough
• BUT…..
2F
2V Mg
Kft f(Qec) * T1/2 / BR
• electromagnetic interactions: e.g. positron - protons, positron - electrons
radiative correction R → R’
• isospin impurity: binding energy difference, configuration mixing
Coulomb correction c = c1 + c2
• nuclear structure dependent radiative correction NS
• if these effects corrected: constant ft value
constant vector current hypothesis (CVC)
• determination of gv via Ft value:
many ft values are needed to test CVC and theoretical corrections
• from gv:
determination of Vud matrix element of CKM quark mixing matrix Vud = gv / gF
Ft = ft (1 + R’ ) (1 – c + NS) = = constant
K2
F2V Mg (1 + R)
Jaus & Rasche, 1987
Towner & Hardy, 2005
Towner & Hardy, 2005
• overall precision: Ft = (3073.5 ± 1.2) s 4 * 10-4
single measurements: < 10-3
• f: f(QEC5) → Q < 2 * 10-8 → < 1keV
• T1/2: T < 10-3
• BR: BR < 10-3
• theoretical corrections: C, R ~ 1% → < 10%
9 “classical” cases
• Q value measurements at JYFLTRAP: 62Ga
T. Eronen et al., 2006
QEC = (9181.07 ± 0.54) keV
• half-life measurement at GSI:
• half-life measurement at JYFL:
G. Canchel et al., 2005
T1/2 = (116.12 ± 0.15) ms
B. Blank et al., 2004
T1/2 = (116.18 ± 0.04) ms
• branching ratio measurement at JYFL:
A. Bey et al., 2007 BR = (99.905 ± 0.026) %
2511- e+e
954 – 62Ga
1388 – 62Ga
2228 – 62Ga
62Ga31 (0+,T=1)
10
12
22
20
32
42
11
3
?
62Zn32 (0+,T=1)0
953.5
953. 5
850
1389
2227
+ Fermi A
nalog. (sa)
99.902%
+ Fermi N
onanalog.
< 0.014%
+ Gamow-Teller
~ 0.022%
1803.5
2343.2
2374
2806
3159
3180.5
3638
0.078(8)%
0.025(7)%
0.014(5)%
0.022(7)%
%26902.99I
New Ft value for 62Ga
sFt 5863074.
10
sft 1643074.
• Q value measurements at ISOLTRAP: e.g. 38Ca
• half-life measurements at ISOLDE using REXTRAP: e.g. 38Ca
S. George et al., 2007
B. Blank et al., 2007
T1/2 =
(450.0±1.6) ms
z0
r0
m =
(-22058.01±0.65) keV
T1/2 = (450.0 1.6) ms
A longitudinal Penning trap filled with Ne as buffer gas
E
Accumulation Cooling Ejection – TOF selection
Buffer gas cooling
Superconducting magnet 3T
PNe ~10-4 mbar in the trapping area
• Q value measurements at ISOLTRAP: e.g. 38Ca
• half-life measurements at ISOLDE using REXTRAP: e.g. 38Ca
S. George et al., 2007
B. Blank et al., 2007
T1/2 =
(450.0±1.6) ms
z0
r0
m =
(-22058.01±0.65) keV
T1/2 = (450.0 1.6) ms
• branching-ratio measurement: 22Mg
• half-life measurement: 34Ar
• other measurements: 62Ga
J. Hardy et al., 2003
V. Iacob et al., 2006
BR = (53.15 ± 0.12) %
T1/2 =
(843.8 ± 0.4) ms
• branching-ratio measurement: 62Ga
• other measurements: 18Ne , 74RbB. Hyland et al., 2006
BR = (99.861 ± 0.011) %
14O T1/2 Leuven, Auckland, Berkeley
QEC Auckland18Ne T1/2 TRIUMF
QEC ISOLDE22Mg T1/2, BR Texas A&M
QEC CPT Argonne, ISOLDE26Si QEC JYFL26Alm QEC JYFL34Ar T1/2, BR Texas A&M
QEC ISOLDE38Ca QEC, T12 ISOLDE
QEC MSU38Km T1/2 Auckland42Sc QEC JYFL42Ti QEC JYFL46V QEC JYFL, CPT Argonne50Mn QEC JYFL
T1/2 Auckland62Ga T1/2, BR GSI, JYFL, TRIUMF, Texas A&M
QEC JYFL74Rb T1/2 ,BR TRIUMF, ISOLDE
QEC ISOLDE
<Ft> = (3074.4 ± 1.2) s gv = 1.1358(4) Vud = 0.9736(4)
• CVC accepted• measurement of ft• test c - NS from theoretical models
• ft value + QED corrections
• ft value with all corrections Ft
nuclear corrections seem to be okey, but they have large uncertainties
new calculations needed + measurements for nuclei with large corrections
ft (1 + R’ ) (1 – c + NS)
b
s
d
VVV
VVV
VVV
b
s
d
tbtstd
cbcscd
ubusud
• coupling of quark weak eigen states to mass eigen states in the Standard Model
unitarity condition:
Vud = 0.9736(4) ~ 95 %Vus = 0.2254(21) ~ 5 %Vub = 0.00367(47) ~ 0 %
Vui² = 0.9987(12)
1VVV 2ub
2us
2ud
Vud 0+ 0+ decays: 0.9736(4)neutron decay: 0.9741(20) Part. Data Group (2004)(Serebrov et al. (2005) not included)pion beta decay: 0.9728(30) larger uncertainty
Vus KX decays + form factor Leutwyler-Roos (1984) Cirigliano et al. (2005)
deviation to
unitarity
Vud
nuclear
0+ 0+
neutron
pdg 04
neutron
Se 05
Vus
K decay: pdg04 ~ 2 ~ 2 ok
K: all results ~ 1 ok ~ 2
• the situation today
Severijns, Beck, Naviliat-Cuncic, 2006
• limit on induced scalar currents:
fs = -0.00005(130) or |fs| 0.0013
• limit for fundamental scalar current:
|Cs / Cv | 0.0013
• limit for Fierz interference term:
bF = 0.0001(26)
Ft =
• limits on right-handed currents: -0.0005 < < 0.0015 (90% C.L.)
W1 = WL cos - WR sin W2 = WL sin + WR cos
• unitarity of first column of CKM matrix:
Vid = 0.9985(54)
best limits from all approaches
Ft value for fs = 0.002
K2 GF
2 Vud2 (1 + V
R) 1
(1 + <b’F>)
Hardy & Towner, 2005
• uncertainty on <Ft> : 3073.3(35) s 3074.4(12) s ==>> 30 % due to more and more precise exp. data
• Fierz term : 0.0010(30) 0.0001(26) ==>> strongly reduced value due to better exp. data
• Vud : 0.9740(10) 0.9736(4) ==>> slight change, factor 2.5
• unitarity test of first row of CKM matrix: Vui = 0.9970(21) Vui = 0.9987(12) ==>> change mainly due to Vus, improved precision from Ft
• unitarity test of first column of CKM matrix: Vid = 0.9985(54) ==>> not evaluated in 1990
• right-handed currents: Re(alr) = -0.0004(6) ==>> not evaluated in 1990
• Tz = -1 nuclei: 10C, 18Ne, 22Mg, 26Si, 30S, 34Ar, 38Ca, 42Ti
- major problems: T1/2 of daughter nuclei BR with precision of 10-3 → absolute efficiency with < 10-3
→ knowledge of source strength - solutions:
trap-assisted spectroscopy for half-life measurementshigh-precision efficiency calibration of single-crystal Germanium
ion counting → experiments on separators like MARS (Texas A&M), LISE3 (GANIL), TRMP (KVI)
• Tz = 0 nuclei: 66As, 70Br, 78Y, 82Nb, 86Tc, …, 98In
- major problem: production rates, for some isomers, excited 0+ states
- solution: future facilities like EURISOL, maybe SPIRAL2, ISOLDE
• theoretical corrections: - new approaches needed for nuclear corrections - higher-order calculations for QED corrections
• half-life of 38Ca at ISOLDE• half-life of 26Si at JYFL• half-life of 42Ti at JYFL or at KVI• calibration of a HP germanium
- branching ratio of 10C, 26Si,
38Ca, 42Ti
• interesting physics case with strong implications
beyond nuclear physics
• lively field with world-wide activities
• high-intensity beams of nuclei of interest are already available
• trap-assisted spectroscopy becomes more and more important,
ISOLDE is a very good place
• LISE3/GANIL and TRIP/KVI could be a prominent place for
new branching ratio measurements
• in Europe: ISOLDE, JYFL, LISE3, TRIP, LIRAT/DESIR can play an
important role
• Q value measurements at ISOLTRAP: e.g. 38Ca
• half-life measurements at ISOLDE: e.g. 38Ca
• other measurements: 18Ne, 22Mg, 34Ar, 74Rb
S. George et al., 2007
B. Blank et al., 2007
T1/2 = (451.8±1.6) ms
z0
r0
• Q value measurements at MSU trap: 38Ca
G. Bollen et al., 2006
• m = 280 eV
• Q value measurements at JYFLTRAP: e.g. 62Ga
• half-life and branching-ratio measurements:
• other measurements: 26Alm, 26Si, 42Ti, 42Scm, 46V, 50Mn
G. Canchel et al., 2005 A. Bey et al. , 2007
T. Eronen et al., 2006
T1/2 = (116.12 ± 0.15) ms
QEC = (9181.07 ± 0.54) keV
• Q value measurements at CPT at Argonne: 46V
• other measurements: 22Mg G. Savard et al., 2005
• half-life measurement: 62Ga
• branching-ratio measurement: 62Ga
B. Blank et al., 2004
G. Savard et al.
T1/2 =
(116.18 ± 0.04) ms
• half-life measurement: 14O
M. Gaelens et al., 2001T1/2 = (70.560 ± 0.049) s
• half-life measurement: 50Mn
• other measurements: 14O, 38Km P.H. Barker et al., 2006
T1/2 = (283.10 ± 0.14) ms
• half-life measurement: 14O
J.T. Burke et al., 2006
T1/2 = (70.696 ± 0.052) s
• half-life measurements:
- only nuclei without “daughter half-life problem”
e.g. 10C, 14O, 18Ne, 30S, ….. 66As, 70Br ??
on LIRAT2 or SIRa
• branching ratio measurements
- top candidates: 18Ne, 26Si, 38Ca, where half-life and QEC are measured
production rates at LISE3: 18Ne: 6000pps with 3A of 20Ne, 100% pure
26Si: 3000pps with 3A of 32S, 100% pure
38Ca: 2500pps with 3A of 40Ca, 100% pure
- others which are feasible: 10C, 14O, 22Mg, 30S, 34Ar, (42Ti)
• integration of decay time
spectrum to yield source strength
(a few percent error)
• intensity of rays
(statistical and systematic error)
branching ratios with large error bars (~ 1%) acceptable for very small branching ratios
Primary beam
SISSI target
spectrometer LISE3 :degrader Be Wien filter