in nuclear decays Oscar Naviliat-Cuncic National Superconducting - - PowerPoint PPT Presentation

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in nuclear decays Oscar Naviliat-Cuncic National Superconducting - - PowerPoint PPT Presentation

Mar 06, 2023 158 likes •402 views

Beta decay as a probe of new physics Fierz interference term in nuclear decays Oscar Naviliat-Cuncic National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy Michigan State University Thanks to: N. Birge, L.

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SLIDE 1

Fierz interference term in nuclear decays

Oscar Naviliat-Cuncic

National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy Michigan State University

Thanks to:

  • N. Birge, L. Broussard, N. Fomin, A. García, X. Fléchard, E Liénard, N. Severijns

Beta decay as a probe of new physics

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SLIDE 2

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 2

General Context

Mainly two ways to search for the presence of the Fierz term in beta decay observables:

  • “Indirect” searches (Ft-values,

correlation coefficients), integrated

  • r differential:
  • “Direct” searches (spectrum shape):
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SLIDE 3

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 3

Current status of S and T constraints

  • “Minimal fit” (LH-n)
  • M. Gonzalez-Alonso, O.N.C., N. Severijns,
  • Prog. Part. Nucl. Phys. in print (2018)

arXiv:1803.08732

  • From contributions of the Fierz term to Ft(0+0+), tn and An
  • Other neutron and nuclear data have very small impact.
  • Constraint on Tensor is ~2 weaker than on Scalar.
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SLIDE 4

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 4

Benchmark uncertainties

  • M. Gonzalez-Alonso, O.N.C, N. Severijns,
  • Prog. Part. Nucl. Phys. in print (2018)

arXiv:1803.08732

  • How good we need to measure?…
  • …to impact couplings in b decay.
  • (complementarity/competition with HE not considered here)
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SLIDE 5

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 5

Sensitivity of recent indirect searches

  • “Dedicated” (KU-Leuven): low temperature nuclear orientation
  • F. Wauters et al., Phys. Rev. C 80

80 (2009) 062501(R):

𝐵 in 114In, DbGT~ 7% (1s)

  • F. Wauters et al., Phys. Rev. C 82

82 (2010) 055502:

𝐵 in 60Co, DbGT~ 3.5% (1s)

  • G. Soti et al., Phys. Rev. C 90

90 (2014) 035502:

𝐵 in 67Cu, DbGT~ 5.1% (1s)

…no impact on constraints

  • “Opportunistic” (TRIUMF): polarized atoms in MOT
  • M. Anholm et al., DNP Meeting 2018, Hawaii:

𝐵 in 37K, Db mix~ 4% (1s)

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SLIDE 6

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 6

Current direct searches and plans

Isotope Method Lab/Institution

6He

thin foil; 4p detector

GANIL/LPC-Caen

??? MWDC+scintillators

Krakow, Leuven

45Ca

source in UCNA spectr.

UT, ORNL, NCSU, KUL++

6He

CRES

UW , ANL++

6He, 20F

Calorimetry

NSCL/MSU, Wittenberg

…explicitly considering the determination of bGT

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SLIDE 7

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 7

Selection of candidates

Kinematic sensitivity

  • M. Gonzalez-Alonso and O. N.-C

PRC 94 94 (2016) 035503

Hadronic corrections

Jp

  • 1

1 b- b+ M1 Jp Jp In an isospin triplet, the weak magnetism form factor can be determined from CVC

20F

6He 20F

Candidates

Uncertainty for 108 events (assuming fit from 5% to 95% of end-point)

45Ca

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SLIDE 8

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 8

Sensitivity to form factors in 6He

4 3 2 1

10 4 . 3 ) 79 ( 22 . 68 6

 D    

GT M WM

b E M b

  • Sensitivity to induced tensor:

5

10 8 . 1

 D D d bGT

  • Sensitivity to weak magnetism:

4

10 2 . 4

 D D

WM GT

b b

  • In A=6 it is not possible to determine d

experimentally from comparison with mirror decay.

  • Calculation: d=2.4, F. Calaprice, PRC 12

12 (1975) 2016 (Due to uncertainty on WM, DbWM = 0.79)

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SLIDE 9

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 9

  • In the decays of A=8, 12, and 20 triplets, it is observed (Barry’s

talk) that dbWM .

  • There is no obvious explanations why d is suppressed in 6He.
  • If the error on d would be Dd = 68.22-2.4 then we get DbGT =

1.3×10-3 !!!

Sensitivity to form factors in 6He

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SLIDE 10

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 10

6He at GANIL

Courtesy: X. Flechard

PM

LED

241Am  source

PM

LED

241Am  source

6He beam (10-20 keV)

Movable 1.5 mm mylar-Al Implantation foil

b- b-

fast fast slow slow

Fast: EJ-204 Slow : YAP or EJ-240 Total charge(arb. Units) Fast/(Fast+Slow) Tests with 90Sr b source EJ-240 & EJ-204 scintillators Pile-up Clean 90Sr b spectrum LED b in fast scint.

241Am 

Calibration with ATRON electron accelerator

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SLIDE 11

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 11

miniBETA (Leuven, Krakow)

Courtesy: N. Severijns (M. Perkowski, Mazurian Lakes Conf. 2017)

  • Beta source inside detector
  • Trigger with plastic scintillators
  • Track with MWDC
  • Tested with cosmics:
  • average efficiency ~90%
  • position resolution ~0.5mm
  • (not clear what source will be used)
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SLIDE 12

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 12

45Ca at LANL

Courtesy: N. Birge, N. Fomin

  • Single crystal Si
  • 100 nm dead layer
  • 1.5 mm thick

Source geometry

  • Recorded waveforms for each pixel
  • 108 events collected
  • MC simulations under way
  • Analysis in progress including corrections

for cross-talk, backscattering, etc.

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SLIDE 13

6He little-b measurement at UW

Goal: measure “little b” to 10-3 or better in 6He Stats not a problem.

  • W. Byron1, M. Fertl1, A. Garcia1, G. Garvey1, B. Graner1, M.

Guigue2, A. Leredde3, P. Mueller3, N. Oblath2 , R.G.H. Robertson1,

  • G. Rybka1, G. Savard3, D. Stancil4, H.E. Swanson1, B.A.

Vandeevender2, F. Wietfeldt5, A. Young4

1University of Washington, 2Pacific Northwest National Laboratory, 3Argonne National Lab, 4North Carolina State University, 5Tulane

Use cyclotron radiation spectroscopy. Similar to Project 8 setup for tritium decay. PRL 114, 162501 (2015)

2 𝜌 𝑔 = 𝑟 𝐶 𝑑2 𝐹 𝐶

Determine e’s energy at birth via cyclotron frequency

Courtesy: A. Garcia 13

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SLIDE 14

6He little-b measurement at UW

Goal: measure “little b” to 10-3 or better in 6He Stats not a problem.

6He in

Presently under construction

Cryo cooler for T≈ 5 K Low-Noise Amps Decay volume 1-7 Tesla superconducting solenoid

6He in 14 Courtesy: A. Garcia

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SLIDE 15

Why do we like the Project-8 technique for 6He?

  • Measures beta energy at creation,

before complicated energy-loss mechanisms.

  • High resolution allows debugging of

systematic uncertainties.

  • Room photon or e scattering does not

yield background.

  • 6He in gaseous form works well with

the technique.

  • 6He ion-trap (shown by others to

work) allows sensitivity higher than any other proposed.

  • Counts needed not a big demand on

running time.

𝜕 = 𝑟𝐶 𝐹 1) Take a wave during 30 ms. Initial frequency  E Time bins ~ 30 ms. 2) Fourier analysis. 3) Plot peak frequency.

15 Courtesy: A. Garcia

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SLIDE 16

Phase I: proof of principle 2 GHz bandwidth. Show detection of cycl. radiation from 6He. Study power distribution. Phase II: first measurement (b < 10-3) 6 GHz bandwidth. 6He and 19Ne measurements. Phase III: ultimate measurement (b < 10-4) ion-trap for no limitation from geometric effect. Mission until

  • Aug. 2020

We have put together a collaboration, written and submitted a proposal. Now kick-started by DOE and UW funds.

16 Courtesy: A. Garcia

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SLIDE 17

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 17

Calorimetric technique at NSCL

6He

  • Eliminates effect of electron backscattering from detectors
  • Chopped beam: implantation/decay

20F

46 MeV/nucleon 132 MeV/nucleon CsI(Na) NaI(Tl) CsI(Na) PVT

MSU: M. Hughes, X. Huyan U.Witt: E. George, P. Voytas From workshop at ACFI

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SLIDE 18

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 18

Data from 20F

  • M. Hughes et al. PRC 97

97 (2018) 054328

10C, 11C beam

induced background

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SLIDE 19

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 19

20F half-life

AFTER 17 combined std. dev. discrepancy!

  • Our result was confirmed by group

from Notre Dame.

  • Level of uncorrelated background is

smaller than 8×10-6

  • M. Hughes et al. PRC 97

97 (2018) 054328

BEFORE

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ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 20

Escape of Bremsstrahlung radiation

For 6He spectrum, the differences correspond to about 5% of the linear term due to WM.

  • X. Huyan et al. NIMA 97

97 (2018) 054328

6He

(relative to Option4)

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SLIDE 21

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 21

Radiative corrections

Theoretical corrections to phase space Sirlin’s g Fayans

20F decay

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SLIDE 22

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 22

Example of fit in 6He

CsI-run145-segs:0,1,2-TwS:0400-0500 CsI-run145-segs:0,1,2-TwB:1000-1100

~100 independent spectra collected with CsI(Na) and NaI(Tl)

  • X. Huyan
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SLIDE 23

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 23

Status and Outlook

  • Current level of statistical sensitivity:
  • 3×10-3 for 20F
  • 1.5×10-3 for 6He (with CsI and NaI detectors)
  • Uncorrelated background in 20F is negligible but the effect of

summing due to Bremsstrahlung and 1.6 MeV photon in implantation detector makes the analysis more complicated.

  • New beam request for 6He is in preparation.
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SLIDE 24

ACFI, Beta decay as a probe of new physics, Nov.1-3, 2018 24

Summary

  • Several innovative experimental approaches are considered

to reach new levels of sensitivity for the measurements of the Fierz term.

  • “Which experimental approaches provide the most

promising probes for new physics…”?