Present status of -decay studies… …in nuclear mirror transitions Oscar Naviliat-Cuncic National...

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.



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



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)



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



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)



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



Status of Vud values

Towner&Hardy@CKM-2010

eepn ee 0



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 /



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



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.



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)



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



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



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



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



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”)



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



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



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.



Future plans

Implantationtape station

Multi Reflection TOFMass Spectometer

Main RFQSmall RFQ

("rebuncher")

New chamberImprovement of total efficiency by a factor ~ 10



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



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



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



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



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.

…/…



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



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



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 /



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)



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+

Present status of -decay studies… …in nuclear mirror transitions Oscar Naviliat-Cuncic National...

Documents

Transcript of Present status of -decay studies… …in nuclear mirror transitions Oscar Naviliat-Cuncic National...