1. Low‐energy precision measurements at the intensity frontier
in nuclear  decay
PSI-2013
Villigen, Sept. 8-12, 2013 b+ ne
Nathal Severijns
Kath. Universiteit Leuven, Belgium

2.  decay correlations to probe new physics
nucleus q
Overview
recent achievements
- - correlation
- -asymmetry
- Ft-values
(selected experiments showing diversity in techniques used)
scalar/tensor currents and Vud
prospects for this field in the LHC era
developments / improvements - extend to other observables
- reach higher precision

3. scalar and tensor currents

4. 1. - correlation to probe scalar/tensor weak currentsne
nucleus q
Fierz term
(assuming maximal P-violation and T-invariance for V and A interactions)
!!! for pure transitions weak interaction info independent of nuclear matrix elements !!!
recoil corr. (induced form factors)  ; radiative corrections  10-4

5. Ion/atom traps for - correlation measurements
Most precise  correlation measurements
Particle traps: ideal sources
- sample is isotopically pure
- localized in a small volume
- atoms decay at rest
- detection of recoil ion
- negligible source scattering
- potential for polarized sample
Penning
Paul
MOT

6. Overview of - correlation projects
N.S. & O. Naviliat-Cuncic, Physica Scripta T152 (2013)

7. TRINAT MOT trap at TRIUMF-ISAC – 38mK - scalar
search for scalar couplings
superallowed 0+  0+
pure Fermi transition
(t1/2 = 0.95 s)
A. Gorelov, J. Behr et al.,
Phys. Rev. Lett. 94 (2005)
TOF

8. 6He Trap/Detector Chamber talk by Frederik Wauters
6He MOT Trap CENPA – Univ. Washington, Seattle P. Mueller, A. Garcia, et al. Argonne Natl. Lab., Univ. Washington, LPC-CAEN, CERN, NSCL, Michigan State Univ.
1083 nm
6He Trap/Detector Chamber
RF discharge -> metastable He*
Laser 1083 nm
Timeline:
- 6He produced and trapped
- first data run in August > 1 % measurement
% measurement by 2015
talk by Frederik Wauters
6He Trapping CENPA: @ source: 5x109 s-1 ; capt. efficiency = trap: 1000 s-1
Trap-to-trap transfer: > 60% efficiency, ~15 ms
A. Knecht et al., NIM A 660 (2011) 43, Phys .Rev. C 86 (2012) & arXiv: v2 [nucl-ex]

9. LPCTrap @ GANIL - 6He / 35Ar - tensor / scalar
2006 (6He): aβν = −0.3335(73)stat(75)syst
X. Fléchard et al., J. Phys. G 38 (2011)
Li3+
Li2+
2010
6He
Da/a ~ 0.5 %
(analysis in progress)
C. Couratin et al.
PRL 108 (2012)
Da/a ~ 0.3%
(analysis in progress)
35Ar

10. talk by Paul Finlay WITCH @ ISOLDE - 35Ar - scalar scalar: a = -1
(KU Leuven, Univ. Munster, ISOLDE, NPI Rez-Prague, LPC-Caen)
Goal : determine bn correlation for 35Ar with (a/a)stat  0.5 %
 measure energy spectrum of recoiling ions with a retardation spectrometer
scalar: a = -1
vector: a = +1
talk by Paul Finlay
M. Beck et al., Eur. Phys. J. A47 (2011) 45
M. Tandecki et al., NIM A629 (2011) 396
S. Van Gorp et al., NIM A638 (2011) 192
6/27/2018

11. O. Aviv et al., J. Phys.: Conf. Ser. 337, 012020 (2012)
6/27/2018
N. Severijns, CGS14 conference - Aug Sept. 02, 2011

12. -- Correlation in Paul trapped 8Li Ions
G. Savard et al. (ANL, Mc. Gill, LLNL, Univ. Chicago, … )
aβν = − (60)stat (67)sys
G.Li, G.Savard et al., PRL 110 (2013)

13. 2. Limits on scalar currents
corrected Ft value of 0+  0 + superallowed pure Fermi transitions :
with
(Fierz term)
= (83) s
Towner & Hardy, Rep. Prog Phys. 73 (2010)
38mK: Gorelov, Behr et al.,
PRL 94 (2005)

14. (K.U.Leuven, NICOLE-ISOLDE, NPI Rez-Prague, Uni Bonn)
3. -asymmetry parameter in nuclear beta decay
(K.U.Leuven, NICOLE-ISOLDE, NPI Rez-Prague, Uni Bonn)
Geant 4
(P from anisotropy of -rays )
60CoCu , Bext = 13 T
114InFe , Bhf = 27 T
67CuFe , Bhf = 21 T
Analysis: I  
IS431-experiment

15. asymmetry parameter – Leuven / ISOLDE
ISOLDE - NICOLE
Louvain-la-Neuve - KOOL
Leuven
Leuven

16. F. Wauters et al., NIM A 609 (2009) 156
Aexp (60Co) = (12)stat (16)syst
(ASM = (9) )
Aexp (114In) = (10)stat (10)syst
(ASM = (3) )
Aexp (67Cu) = (6)stat (11)syst
(ASM = (2) )
region
analysed
F. Wauters et al., Phys. Rev. C 82 (2010)
F. Wauters et al., Phys. Rev. C 80 (2009) (R)
F. Wauters et al., Phys. Rev. C 80 (2009) (R)
G. Soti et al., to be submitted
poster by Gergelj Soti
major systematic errors:
performance of GEANT code (scattering)
determination of nuclear polarization

17. Constraints on tensor type weak couplings talk by Frederik Wauters
a(6He)
C. Johnston et al.,
PR 132 (1963) 1149
A(60Co)
F. Wauters, N.S. et al.,
PR C 82 (2010)
--(8Li)
G.Li, G.Savard et al.,
PRL 110 (2013)
A(67Cu)
G. Soti, N.S. et al., (2013) submitted
A(67Cu)
A(60Co)
--(8Li)
a(6He)
talk by Frederik Wauters

18. Precision measurements in nuclear/neutron  decay in the LHC era
nuclear and neutron decay, pion decay
limits on scalar/tensor couplings
obtained by CMS collaboration in
pp  e + MET + X channel
- S. Chatrchyan et al. (CMS Collab.)
J. High. Energ. Phys (2012) 023;
- CERN Rep. nr. CMS-PAS-EXO (2013)
O. Naviliat-Cuncic and M. Gonzalez-Alonso
Annalen der Physik 525 (2013) 72.
V. Cirigliano, et al.,
J. High. Energ. Phys (2013) 046

19. Vud quark mixing matrix element

20. 4.  decay correlations and Ft values of the mirror  transitions
- correcting Ft values of mirror  transitions for GT/F mixing ratio  Vud
N.S. , I.S. Towner et al.,
Phys. Rev. C 78(2008)
19Ne, 21Na, 29P, 35Ar and 37K
|Vud| = (17)
O. Naviliat-Cuncic & N.S. , Phys. Rev. Lett. 102 (2009)
- GT/F mixing ratio  from correlation coefficients:
e.g and J   A

21.  decay correlations and Ft values of the mirror  transitions
New beta decay correlation measurements with mirror nuclei:
Vud for relative precision of 0.5% on a or A :
a(35Ar)  Vud = (data from GANIL-LIRAT being analysed)
a(19Ne)  Vud = (run in Nov 2013 at GANIL-LIRAT)
beta asymmetry A(35Ar) is most sensitive to Vud :
A(35Ar)  Vud = with present Ft value
A(35Ar)  Vud = if Ft value is improved by factor 5
(requires QEC, T1/2 and BR)
Note: Vud (0+  0+) =
only factor of 2 !!
N.Severijns & O. Naviliat-Cuncic, Physica Scripta T152 (2013)

22.  decay correlations and Ft values of the mirror  transitions
- ongoing project at GANIL for - correlation
- A(mirror) at NSCL/BECOLA and at ISOLDE/COLLAPS-VITO
(Leuven, MSU, … )
- collinear laser optical pumping
- 35Ar, …
- A(35Ar) with MOT (Leuven, ULiège, … )
- measurements of : QEC, t1/2 and BR for mirror transitions
ongoing / planned at several facilities
ISOLDE, JYFL, GANIL, TRIUMF, …

23. induced / recoil terms
weak magnetism

24. include induced / recoil terms
due to strong interaction;
decaying quark is not free but bound in a nucleon
- effects of few per mille typically
- dominant = ‘weak magnetism’
theoretical study:
induced terms for mirror decays and
T = 1 triplet decays, up to A = 45:
( V. De Leebeeck, I.S. Towner, N.S., to be published )
experimental study:
new spectrometer for  spectrum shape
measurements (MWDC + E-detectors)
Leuven-Krakow collaboration

25. induced / recoil terms mirror  transitions
x  decays of triplet states
avg = 5.6(30)
V. De Leebeeck, I.S. Towner, N.S., et al., to be published

26. induced / recoil terms mirror  transitions avg = 0.97(10)
mirror (49)
(A = 3-45)
triplet (15)
(A = 6-30)
V. De Leebeeck, I.S. Towner, N.S., et al., to be published

27.  spectrum shape measurements with the miniBETA spectrometer
Univ. Krakow – Univ. Leuven
1. low -endpoint energies
( 45Ca, 60Co, 67Cu … ) :
 scalar / tensor type
weak interactions
2. high -endpoint energies
(68Cu, 114In, … ) :
weak magnetism
3. improve current knowledge
on electron scattering
 improve precision of Geant4
multi-wire drift chamber
scintillator

28. commissioning ongoing at Krakow
miniBETA spectrometer
poster by Gergelj Soti
commissioning ongoing at Krakow

29. Summary - - correlation and  asymmetry measurements + Ft-values
 improved limits on scalar and tensor charged weak currents;
- correlation measurements and Ft-values of mirror  transitions
 contribute to further improving precision of Vud mixing matrix element;
- searches for new physics at low energies remain competitive
with direct searches at LHC when concentrating on Fierz term and Vud
- need to include induced (recoil) terms in interpretation of experiments
 efforts to extend our understanding of these ongoing
- many experiments ongoing or planned / in preparation