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Present status of Present status of -decay studies… -decay studies… …in nuclear mirror transitions…in nuclear mirror transitions
Oscar Naviliat-CuncicNational Superconducting Cyclotron Laboratoryand Department of Physics and AstronomyMichigan State University
FUNTRAP workshop, Rehovot, December 2-6, 2012 2
Michigan State UniversityNational Science Foundation
Scope and outline
1. Definitions2. Status of the strength of the weak interaction in -decay3. Recent results and plans:
- spectroscopic quantities- theory- decay correlations
4. Summary
• Stress the role of -decay experiments in mirror nuclei to test the structure of the weak interaction.• Review recent results in theory and experiments and describe future plans to improve the determination of the weak strength in mirror transitions.
FUNTRAP workshop, Rehovot, December 2-6, 2012 3
Michigan State UniversityNational Science Foundation
Nuclear mirror transitions
J, T=1/2
J, T=1/2
QECBR
t1/2
• Super-allowed transitions between isobaric analogue states within T=1/2 doublets.
• Occur in mirror nuclei, between states with same spins and parities.
• Involve the vector (V) and axial (A) components of the weak interaction (in SM)
neutrons
prot
ons
• Many candidates (Z=N+1)• All (except n and 3H)
• In practice: a dozen
Z = N+1
Zmax ≈ 40-45
FUNTRAP workshop, Rehovot, December 2-6, 2012 4
Michigan State UniversityNational Science Foundation
Strength of the weak interaction
Pure leptonic Semi-leptonic(non strange)
Semi-leptonic(strange)
W
d
e e
d du u
u
n p
W
ee
g
g
W
s
d du u
u
p
e e
GF g2 GV = GF cosC G = GF sinC
C 13°)
C (Cabibbo angle)
FUNTRAP workshop, Rehovot, December 2-6, 2012 5
Michigan State UniversityNational Science Foundation
Generalization to three quark generations
• The Cabibbo scheme was generalized to 3 generations of quarks by Kobayashi and Maskawa.
V tbV tsV td
V cbV csV cd
V ubV usV ud
V CKM
V tbV tsV td
V cbV csV cd
V ubV usV ud
V CKM
b
s
d
V
b
s
d
CKM
b
s
d
V
b
s
d
CKM
Masseigenstates
Weak eigenstates
Cabibbo-Kobayashi-Maskawa (CKM) matrix
Vud = cosC
FUNTRAP workshop, Rehovot, December 2-6, 2012 6
Michigan State UniversityNational Science Foundation
Determination of Vud
Pure leptonic Semi-leptonic(non strange)
W
d u
W
g gVud
Compare the -decay rate of a (simple) system made out of u and d quarks with the muon decay rate.
(at tree level)
FUNTRAP workshop, Rehovot, December 2-6, 2012 7
Michigan State UniversityNational Science Foundation
Vud from mirror transitions
|Vud| = 0.9719(17)
• Dominated by experimental errors
O. N-C and N. Severijns, PRL102 (2009) 142302
K: constantGF: Fermi constantgV = 1 (if CVC holds)R: SM radiative correction
FUNTRAP workshop, Rehovot, December 2-6, 2012 8
Michigan State UniversityNational Science Foundation
Status of Vud values
Towner&Hardy@CKM-2010
eepn ee 0
FUNTRAP workshop, Rehovot, December 2-6, 2012 9
Michigan State UniversityNational Science Foundation
Error budget on Ft-valuesN. Severijns and O.N-C, Annu. Rev. Nucl. Part. Sci. 61 (2011) 23
• Errors dominated by those on mixing ratio,
X ≡ never measured
FVGTA MCMC /
FUNTRAP workshop, Rehovot, December 2-6, 2012 10
Michigan State UniversityNational Science Foundation
Spectroscopic quantities
J, T=1/2
J, T=1/2
QECBR
t1/2
Example: 19Ne half-life (s)
Parent Observable Group(s)/Labnucleus
19Ne t1/2 TRIUMFTUNL@KVIGANIL
21Na t1/2 TUNL@KVI29P t1/2 CENBG@JYFL31S t1/2 CENBG@JYFL
BR CENBG@JYFLQEC JYFL
37K t1/2 TUNL@KVI39Ca t1/2 CENBG@ISOLDE TRIUMF: S. Triambak et al. PRL109 (2012) 042301
KVI: (PRELIMINARY) L. Broussard, PhD thesis, Duke University, 2012GANIL: (PRELIMINARY) P. Ujic, F. de Oliveira Santos, priv. com.
Similar to 0+→0+ transitions
• Pre
cision: 2
.8×10-4
• New pro
posal a
t GANIL
to go below the 10
-4 leve
l
FUNTRAP workshop, Rehovot, December 2-6, 2012 11
Michigan State UniversityNational Science Foundation
Theoretical corrections (T=1/2)
• SM-WS: N.Severijns et al., PRC 78 (2008) 055501• DFT-Skyrme: W. Satula et al., arXiv: 1210.1128v2
• Negligible impact on Ft-value at the present level of precision.
FUNTRAP workshop, Rehovot, December 2-6, 2012 12
Michigan State UniversityNational Science Foundation
Measurements of correlations
FVGTA MCMC / “Mixing ratio”
A A
J pe
B B
J pv pe
pv
a aBeta asymmetry Neutrino asymmetry angular correlation
Parent Observable Group(s)/Labnucleus
19Ne a LPC-Caen@GANIL21Na A NSCL)23Mg (A NSCL)35Ar a LPC-Caen@GANIL37K a, A, B TRIUMFA NSCL)
Next talk (Dan Ashery)
FUNTRAP workshop, Rehovot, December 2-6, 2012 13
Michigan State UniversityNational Science Foundation
Measuring principleProductionof radioactive nuclei
Separate, slowing downcool, bunch
Trapping ions and measure TOF of recoils relative to
pv
pe
pR pe pv
e
LPCTrap setup at GANIL
FUNTRAP workshop, Rehovot, December 2-6, 2012 14
Michigan State UniversityNational Science Foundation
Beam manipulation
6He+
19Ne+
35Ar+
Ekin : 10 keV 100 eV-1 eV 1 keV 100 eV 0 eV
RFQPulsed cavities Paul trap
E 20 eV 1 eV 0.10 eV
• Overall efficiency: ~1% at 200 ms duty cycle
FUNTRAP workshop, Rehovot, December 2-6, 2012 15
Michigan State UniversityNational Science Foundation
LPCTrap and detectors
recoil
• Deduce correlation from detection of recoil ions in coincidence with particles. • Continuous injection/extraction of ion bunches
into the Paul trap• Measure energy and position of particles• Measure TOF and position of recoil ions
• Over-determination of decay kinematics• Register trap RF phase at decay time• Measure extracted ions for each filling
Paul trap
FUNTRAP workshop, Rehovot, December 2-6, 2012 16
Michigan State UniversityNational Science Foundation
A short digression through 6He decay• 3x108 6He /s• E~20 eV @ 10 keV• emittance: 80 mm.mrad(cooling/bunching)
(Setup 2006-2009)
• The only trap for measurement of a with 6He+ ions operational since 2006!• Reached (a/a)stat < 0.3 % (2010 run)• Goal (a/a) ~ 0.1 % seems feasible with new setup
Old detection setup: short TOF base
FUNTRAP workshop, Rehovot, December 2-6, 2012 17
Michigan State UniversityNational Science Foundation
6He resultsTOF spectrum of recoiling ion
• Proof of principle…X. Fléchard et al.,PRL101 (2008) 212504
• …data analysisX. Fléchard et al.,JPG 38 (2011) 055101(highlight 2011)
(already been “2nd best”)
FUNTRAP workshop, Rehovot, December 2-6, 2012 18
Michigan State UniversityNational Science Foundation
A funny systematic effect
6He+ 6Li2+
Sudden change of central potential
6Li2+
6Li3+
Shake-off
excited(gs)
Different charge states are affected differently by the RF field.Potential distortion of TOF spectrum.
Separate charge states by TOF
e 266 LiHe
FUNTRAP workshop, Rehovot, December 2-6, 2012 19
Michigan State UniversityNational Science Foundation
Shake-off measurement
6Li2+ 6Li3+
Nov. 2010
(Pso )exp= 2.348(35)%
C. Couratin et al., PRL 108 (2012) 243201
• Confirm systematic effect on TOF due to shake-off is negligible.• Have a new little peak which is useless for extracting a and has no real physical interest.
How to turn something useless into something fun ?
6Li2+
6Li2+
6Li3+
excited(gs)
21s|ns (Psu + Pso = 1)
Final n state in 6Li2+
(Pso)QM = 1 - = 2.3364%
Ideal experimental conditio
ns to illustra
te elementary QM
calculations (sudden approximation in Hydrogen like
systems)… just fu
n (…and the re
ferees loved it!)
QM exercise
FUNTRAP workshop, Rehovot, December 2-6, 2012 20
Michigan State UniversityNational Science Foundation
4000 5000 6000 7000 8000 9000 10000 11000
0
200
400
600
800
1000
Cl5+ Cl4+Cl3+
Cl2+
Cou
nts
Time of flight (ns)
Cl+
Measurements in mirror transitions
35Ar (test: June 2011; run: June 2012)• Precision expected a/a ~ 0.3 %• Analysis under way
19Ne (proposal accepted; run: 2013)• Precision goal a ~ 0.3 %
ee 03535 ClAr
• Only “universal” trap so far to measure a .• Can measure a from any separated/cooled beam produced at SPIRAL (new program with alkalis)• The only existing device that can measure charge state distributions following -decay of ions.
FUNTRAP workshop, Rehovot, December 2-6, 2012 21
Michigan State UniversityNational Science Foundation
Future plans
Implantationtape station
Multi Reflection TOFMass Spectometer
Main RFQSmall RFQ
("rebuncher")
New chamberImprovement of total efficiency by a factor ~ 10
FUNTRAP workshop, Rehovot, December 2-6, 2012 22
Michigan State UniversityNational Science Foundation
Measurement of relative -asymmetry
J
J
J’
Mixed
GT
)cos1()( c
vPAEW
Decay rate
GTGT
mixmix
GT
mix
vPA
vPAr
cos
cos
Asy
Asy
• P cancels• AGT exactly known
In practice:• The measured in singles include also the contribution from GT branch• Geometrical cuts (energy, angle) at target and detectors enter as a ratio (MC)
A A
J pe
Beta asymmetry
FUNTRAP workshop, Rehovot, December 2-6, 2012 23
Michigan State UniversityNational Science Foundation
Selection of candidates
J
J
J’
Mixed
GT
21Na 23Mg 37K
Optical pumping scheme;relaxation?…
Control of nuclear polarization via GT transition
Experimental constraints for measurements of A
Mirror transition
FUNTRAP workshop, Rehovot, December 2-6, 2012 24
Michigan State UniversityNational Science Foundation
Polarized low energy beam: BECOLA
77K Cooler/buncher
Laser
Charge exchange cell
Polarization by optical pumping
60 keV beam
P. Mantica & K. Minamisono
BECOLA = BEam COoling and LAser Soectroscopy
detectors
array
2T magnets
FUNTRAP workshop, Rehovot, December 2-6, 2012 25
Michigan State UniversityNational Science Foundation
Statistical estimates
21Na 23Mg 37K
QEC (keV) 3548 4057 6149
E (keV) 351 440 2796
B (%) 5.0 8.2 1.8
T1/2 (s) 22.5 11.3 1.23
ASM 0.861 -0.558 -0.574
SM -0.703 0.543 0.587
A/A (10-3) 4.6 3.8 15
• Assumptions: 105 s-1 low energy beam; <P> = 10%; 2x2 spectrometer; 8 CsI(Tl) modules; 5 days continuous running.
• Dominated by statistics in the GT branch
FUNTRAP workshop, Rehovot, December 2-6, 2012 26
Michigan State UniversityNational Science Foundation
Summary
• For the studies of the weak interaction, neutron and nuclear mirror decays probe the same physics. (neutron decay is the simplest mirror transition).
• Nuclear mirror transitions have shown to provide competitive inputs within the SM (Vud).
• Much activity has been triggered to improve the data for the determination of Vud from mirror transitions.
• Precision measurements of decay correlations in nuclear mirror transitions can contribute to the improved determination of SM parameters and the search for new physics.
…/…
FUNTRAP workshop, Rehovot, December 2-6, 2012 27
Michigan State UniversityNational Science Foundation
In memory of Stuart Freedman• The trace of Stuart is also behind the study of mirror transitions, and in particular in the measurements of correlations.
…and in unpublished documents
FUNTRAP workshop, Rehovot, December 2-6, 2012 28
Michigan State UniversityNational Science Foundation
In memory of Stuart FreedmanNSF proposal(circa ~1996)
• Another example among elegant experiments/ideas by Stuart.• It will be a nice tribute if we succeed to measure at least one candidate with sufficient precision.
→
(J. Torres-García)
X Latin American X Latin American Symposium on Nuclear Symposium on Nuclear Physics and ApplicationsPhysics and ApplicationsDecember 2-6, 2013Universidad de la RepublicaMontevideo, Uruguay
R. Donangelo (chair)G. Gonzalez-Sprinberg (UdelaR)O. Naviliat-Cuncic (MSU)C. Salgado (Jlab)
Nuclear reactions and phases of nuclear matter -- Nuclear and particle astrophysics -- Fundamental symmetries and neutrinos -- Nuclear instrumentation and applications
FUNTRAP workshop, Rehovot, December 2-6, 2012 30
Michigan State UniversityNational Science Foundation
Impact from asymmetry measurementsN. Severijns and O.N-C, Annu. Rev. Nucl. Part. Sci. 61 (2011) 23
• Arrows indicate impact from A/A = 0.2%.
X ≡ never measured
FVGTA MCMC /
FUNTRAP workshop, Rehovot, December 2-6, 2012 31
Michigan State UniversityNational Science Foundation
Corrections
1. Recoil effect: change in the central potential due to recoil
6He+6Li2+
e Pso = (2.3381 + 0.0041ER)%
(ER)max = 1.4 keV
2. Duration of central potential variation (~10-19 s )
Pso = 0.02%
<Pso >= 2.322% (corrections are small)
FUNTRAP workshop, Rehovot, December 2-6, 2012 32
Michigan State UniversityNational Science Foundation
Ionization after beta decay
process Theo1 Theo2 Exp3
single ionization 10.5(1.5) 10.44 10.4(2)
double ionization 0.32 0.042(7)
• The simplest system so far for which theo./exp. comparisons were available
1. A. Winther Dan. Mat. Fys. Medd. 27(1952)1
2. L. Wauters and N. Vaeck PRC 53(1996)497
3. T.A. Carlson et al. PR 129(1963) 2220
6He 6Li+
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