Searching for new physics in the Nucleus

Presentation to REU Students

July 2012

Weak interactions in nuclei: a probe to search for new physics

While the LHC searches at the energy frontier.

Alejandro Garcia

University of Washington

Precision experiments in nuclear beta decays can be more sensitive in some specific areas

Students David Zumwaltand Andy Palmer look at the device they built to produce 6He at UW

6He collaboration: searches for Tensor currents.

P. Muller, Z.-T. LuArgonne National Lab

O. Naviliat-CuncicNSCL, Michigan State University

X. Fléchard , E. LiénardLPC-Caen, Caen, France

Z. Alexander, Y. Bagdasarova, T. Cope, A. Garcia, G. Harper, D. Hertzog, R. Hong, P. Kammel, A. Knecht, H.E. Swanson, D. Zumwalt

University of Washington

Are weak decays carried only by W’s?

e+W

d

u

e+e

Or is there something new?

?u

d e+e

Lepto-Quarku

de+

e

Helicities in the Standard Model

The electro-weak interactions are mediated by VECTOR (Spin=1) particles (Photon, Z0, Ws)

A consequence is that the interactions don’t flip helicities.

max

.JpJp

HExample: photons have H =±1.

Or equivalently (notice anti nu):

All the particles that couple to the Weak interactions are left handed;

Particles Left handedAnti particles Right handed

Helicities in the Standard Model

Consequence: e-antinu correlationIf the nuclear spins don’t flip then the leptons have total Jz=0

Ep

Ep

dd

e

e

e

1

Consequence: e-antinu correlationIf the nuclear spins flip then the leptons have total Jz=1

Ep

Ep

dd

e

e

e

1

Helicities in with Scalar or Tensor Currents

Consequence: e-antinu correlationIf the nuclear spins don’t flip then the leptons have total Jz=0

Ep

Ep

dd

e

e

e

1

Consequence: e-antinu correlationIf the nuclear spins flip then the leptons have total Jz=1

Ep

Ep

dd

e

e

e

1

Searching for tensor currents in 6He

6He

6Li

Instead of detecting the neutrino, determine momentum of electron and 6Li

Solution: hold 6He with light!

Problem: slow 6Li, will loose momentum in ANY supporting layer.

0+

1+

Le

R

TTRe

L

TTif

Le

L

Aif

eCCeCC

eCH

)()(

2''

55

e

e

e

e

Emb

Ep

Epadwdw

10

Decay rate:

2'22

2'22

2

231

TTA

TTA

CCC

CCCa

2'22

'

2

2Re

TTA

TTA

CCC

CCCb

Interaction for GT transitions

Magneto‐Optical Trap

• Six orthogonal, counter‐propagating beams of opposite circular polarization are red‐detuned as in the Doppler cooling configuration

• Anti‐Helmholtz coils introduce a quadrupole field with zero magnetic field at the center and linearly increasing field in the directions of the lasers

Production of 6He at Seattle via 7Li(d,3He)6He

Now have a reliable source of 6He yielding 109 atoms/s in a clean room!A High‐Intensity Source of 6He Atoms for Fundamental ResearchA. Knecht et al.NIM A. 660, 43 (2011)

Extracting gA from the lifetime of 6He

• Two previous experiments disagreed by 9 ms. Resolved the discrepancy.

• Our results in combination with ab‐initio calculations shows that quenching is at most about 2%.

Trapping of 6He• RF discharge in xenon/krypton to excite 

into metastable state• Cycling on 1083 nm transition to 

transversely cool, slow down and trap magneto‐optically

• Trapped atoms transferred to detection chamber with dipole trap

• Based on experience from 6He, 8He charge radius measurements by ANL collaborators:L.‐B. Wang et al., PRL 93, 142501 (2004)P. Mueller et al., PRL 99, 252501 (2007)

6He Little a, detection

• Electron and 6Li recoil nucleus detected in coincidence

• E‐E scintillator system for electron detection (energy, start of time‐of‐flight)

• Micro‐channel plate detector for detection of recoil nucleus (position, time‐of‐flight)

We have already trapped about 500 atoms of 6He at CENPA. But need a more stable source for e‐n 

correlation experiment.

Recent work on low‐energy nuclear physics

Nuclear Astrophysics

22Na(p,) and expected gammasignatures from Novae.

-in collaboration with TRIUMF

A. Sallaska et al.PRL 105, 152501 (2010)PRC 83, 034611 (2011)

!telescopes-gamma with observedbeen yet not hasit why explains

Partially thought!previouslythan higher times3about is rate ),Na(

that revealed tsmeasuremenOur 22 p

Measurement of largest isospin breaking correction and determination of Vud.

D. Melconian et al.PRL 107, 182301 (2011)

angle. mixing quark weak theVud, gdetermininin important are that nscalculatio oftest

stringent afor allowed tsmeasuremenOur

Fundamental symmetries

Recent work on low‐energy nuclear physicsSearches for Time-ReversalSymmetry breaking .

-in collaboration with NIST, Berkeley, Michigan…

P. Mumm et al. (emiT collaboration)PRL 107, 102301 (2011)

decays betanuclear in ofbreakingfor search senstiveMost

T

Determination of the axial couplingConstant with Ultra-cold neutrons.

angle. mixing quark weak theVud, gdetermininin important are that nscalculatio oftest

stringent afor allowed tsmeasuremenOur

Fundamental symmetriesFundamental symmetries

J. Liu et al. (UCNA Collaboration)Phys. Rev. Lett. 105, 181803 (2010)