Electron Capture Of Potassium-40 40 Presented by: Matthew Stukel, - - PowerPoint PPT Presentation

KDK: Measuring The Direct To Ground State Electron Capture Of Potassium-40 40

Presented by: Matthew Stukel, Queen’s University on behalf of the KDK collaboration For the TAUP 2019 Conference 2019/09/12

KDK Collaboration

KDK Collaboration

• N. Brewer[1], H. Davis[3],P. Di Stefano[2], A. Fijalkowska[1][5][6], Z. Gai[1], C. Goetz[3], R.

Grzywacz[3],L. Hariasz[2] ,J. Kostensalo[7], P. Lechner[8], Y. Liu[1], E. Lukosi[3],M. Mancuso[9], D. McKinnon[3], C. Melcher[3], J. Ninkovic[8], F. Petricca[9], C. Rasco[1],

• K. Rykaczewski[1], D. Stracener[1], J. Suhonen[7], M. Wolińska-Cichocka [1][4][6], Itay

Yavin

[1] Oak Ridge National Lab (ORNL), Tennessee, USA [2] Queen’s University, Kingston, Ontario [3] University of Tennessee, Knoxville, Tennessee [4] Heavy Ion Laboratory UW, Warsaw, Poland [5] University of Warsaw, Warsaw, Poland [6] Joint Institute for Nuclear Physics and Applications [7] University of Jyvaskyla, Jyvaskyla, Finland [8] MPG Semiconductor Laboratory, Munich, Germany [9] Max Planck Institute for Physics, Munich, Germany

Technical and Electronic Support from M. Constable, F. Retiere (TRIUMF), K. Dering (Queen’s University), Paul Davis, University

• f Alberta

Overview

1.What is KDK? 2.KDK Experiment 3.KDK Status (Calibration/Efficiency)

What is KDK?

• Pun for “Potassium

Decay”

• KDK is an international

collaboration dedicated to the measurement of the unique thir ird forbidden electron capture decay of 40K

[5] Di Stefano, P.C.F et. Al. 2017. The KDK (potassium decay) experiment. arXiv preprint arXiv:1711.04004.

• Rare example of a uniq

ique th thir ird forbid idden electron capture decay

• Ne

Never been experimentally ly measured

• 40K (0.0117%) can be found in natural potassium

which is a contaminant in NaI

• 40K is a background in many dark matter

experiments (DAMA, SABRE, COSINE-100,etc..)[1]

• Can help with interpretation as a dark matter

signal (See extra slide)

• Increase accuracy in K-Ar

Ar (A (Ar-Ar) dati ting

• Important Decay Channels:
• 10.55 % to Ar-40* through electron capture, EC*
• 0.2 % to Ar-40 through electron capture, EC
• β- is the dominant decay channel

Why 40K?

[1] Pradler, Josef, Balraj Singh, and Itay Yavin. "On an unverified nuclear decay and its role in the DAMA experiment." Physics Letters B 720.4-5 (2013): 399-404.

The different branching ratios of 40K (EC)

LOGFT Value Indirect Experimental Half-Life Value Recent NNDC Value (2017) KDK Theoretical Value

𝐶𝑆𝐹𝐷 = 0.2 1 % 𝐶𝑆𝐹𝐷 = 0.8 8 % 𝐶𝑆𝐹𝐷 = 0.046(6)% 𝐶𝑆𝐹𝐷 = 0.064(19)%

From private communication with J. Kostensalo

[1] Pradler, Josef, Balraj Singh, and Itay Yavin. "On an unverified nuclear decay and its role in the DAMA experiment." Physics Letters B 720.4-5 (2013): 399-404. [2] Endt, P.M., 1990. Energy levels of A= 21–44 nuclei (VII). Nuclear Physics A, 521, pp.1- 400. [3] Be, M.M., Chiste, V., Dulieu, C., Mougeot, X., Chechev, V., Kondev, F., Nichols, A., Huang, X. and Wang, B., 1999. Table of Radionuclides (Comments on evaluations). Monographie BIPM- 5, 7.

KDK Experiment

• A small, inner detector will trigger on the X-rays from 40K
• The internal detector will be surrounded by an larger detector in order to tag the 1460

keV gammas

• This will allow us to separate the events caused by the EC* decay from the direct EC

𝐶𝑆𝐹𝐷∗ 𝐶𝑆𝐹𝐷 = κ

MTAS - External Detector

• The external detector is the Modular Total Absorption Spectrometer (MTAS) from Oak Ridge National Lab (ORNL)
• The MTAS detector consists of 19 NaI(Tl) hexagonal shaped detectors (53cm x 20cm) weighing in at ~54 kg each
• MTAS can provide ~4π coverage on tagging the 1460 keV gammas
• A high efficiency is needed to avoid false positives from the EC* channel and other background sources

[4] Karny, M., Rykaczewski, K.P., Fijałkowska, A., Rasco, B.C., Wolińska-Cichocka, M., Grzywacz, R.K., Goetz, K.C., Miller, D. and Zganjar, E.F., 2016. Modular total absorption spectrometer. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 836, pp.83-90.

SDD - Internal Detector

SDD - Internal Detector Chamber

40K Source Development

• ELECTRON BEAM DEPOSITION
• The electron beam is created by heating up a tungsten filament
• The released electrons are focused towards the tantalum crucible where 3.0 mg of enriched (16% 40K) KCl is

placed

• The heat causes the KCl to evaporate and deposit on the graphite disk placed above
• Testing thickness of the source was 11 μm, while actual source used is 5 μm

KDK Experimental Setup

SDD Energy Spectrum Sample

X-ray Peaks Silicon Escape Peak β+ and other backgrounds Auger Electrons

SDD Energy Calibration

https://indico.cern.ch/event/606690/contributions/2591588/att achments/1497885/2333083/DiStefano_KDK_TAUP_2017.pdf

Data Analysis: 54Mn

• Tagging efficiency = When the SDD is triggered what is the probability of MTAS detecting the

associated gamma

• Need to know efficiency to ~0.5% in order to make desired 40K measurement
• 54Mn source used to find our gamma tagging efficiency at 835 keV
• Ideal due to the non-existent EC to ground state

Data Analysis: 54Mn Efficiency

• Efficiency is calculated by comparing the number of expected coincident and anti-coincident

54Mn x-rays against the measured ones

• At a 1 μs coincidence window the efficiency was measured to be 97.72 +/- 0.01 % @ 835 keV
• 55Fe contamination due to source production, visible at the 6.4 keV Kβ peak

Preliminary Preliminary

40K Measurement (Blinded)

40K visible in MTAS/SDD setup!

40K Comparison with Simulations

Extra Physics

• 88Y has a third forbidden decay as well. Has never been

experimentally measured (barely even theoretically predicted)

• Use of the KSr2I5 scintillator as inner detector (See backup slide)
• 110mAg: For reactor neutron flux measurements

Summary

• KDK is an experiment dedicated to the measurement of a

rare decay of 40K

• Uses a large outer detector MTAS and a small inner

detector, SDD

• 33 days of data has been taken with a custom 40K source
• Data analysis is ongoing with results expected to be

published soon!!!

References

1) Pradler, Josef, Balraj Singh, and Itay Yavin. "On an unverified nuclear decay and its role in the DAMA experiment." Physics Letters B 720.4-5 (2013): 399-404. 2) Endt, P.M., 1990. Energy levels of A= 21–44 nuclei (VII). Nuclear Physics A, 521, pp.1-400. 3) Be, M.M., Chiste, V., Dulieu, C., Mougeot, X., Chechev, V., Kondev, F., Nichols, A., Huang, X. and Wang, B., 1999. Table of Radionuclides (Comments on evaluations). Monographie BIPM-5, 7. 4) Karny, M., Rykaczewski, K.P., Fijałkowska, A., Rasco, B.C., Wolińska-Cichocka, M., Grzywacz, R.K., Goetz, K.C., Miller, D. and Zganjar, E.F., 2016. Modular total absorption

• spectrometer. Nuclear Instruments and Methods in Physics Research Section A:

Accelerators, Spectrometers, Detectors and Associated Equipment, 836, pp.83-90. 5) Di Stefano, P.C.F., Brewer, N., Fijałkowska, A., Gai, Z., Goetz, K.C., Grzywacz, R., Hamm, D., Lechner, P., Liu, Y., Lukosi, E. and Mancuso, M., 2017. The KDK (potassium decay)

• experiment. arXiv preprint arXiv:1711.04004.

6) Stand, L., Zhuravleva, M., Lindsey, A. and Melcher, C.L., 2015. Growth and characterization

• f potassium strontium iodide: A new high light yield scintillator with 2.4% energy
• resolution. Nuclear Instruments and Methods in Physics Research Section A: Accelerators,

Spectrometers, Detectors and Associated Equipment, 780, pp.40-44.

Extra Slides

40K Effects On Annual Modulation Experiments

• The uncertainty on BREC could have an effect on the interpretation of the DAMA signal as a dark

matter claim

• A high branching ratio would imply a larger Bo, meaning less room for So and thus a higher allowed

modulation fraction. (Sm/So)

• This could rule out potential dark matter models that explain an annual modulation signal

𝑡𝑛 = 𝑇𝑛 𝑇𝑝 𝑆 𝑢 = 𝑆𝑝 + 𝑇𝑛(𝑢) 𝑆 𝑢 = 𝐶𝑝 + 𝑇𝑝 + 𝑇𝑛(𝑢) 𝑡𝑛 = 𝑇𝑛 𝑆𝑝 − 𝐶𝑝 𝑡𝑛 = 𝑇𝑛 𝑆𝑝 − 𝐶𝑔𝑚𝑏𝑢 − 𝐶𝑙40

APD vs. SDD

MTAS Background Spectrum

• Background Spectrum for the MTAS detector
• Run Length: 16.7 hrs
• The background rate of events in the 1460 keV full collection peak (100 to 4000 keV) ~2400 events/s

40K: 1460 keV 218Bi: 1760 keV 208Tl: 2614 keV 127I and 23Na neutron capture peak

Electron Stopping Distance in Silicon

• Grey: Dead Layer, Orange: SiO2 Dead Layer, Red: Neutral p+layer (Dead Layer Region), Pink: Depleted n-layer,

X-Ray Transmission probability in SDD

• Transmission probability of different

energy x-rays

• Transmission probability = Chance it will

make it to that specific distance in silicon

Unique Third Forbidden Decay

l ΔJ ΔP Super Allowed No Allowed 0, 1 No First Forbidden 1 0,1,2 Yes Second Forbidden 2 1,2,3 No Third Forbidden 3 2,3,4 Yes Fourth Forbidden 4 3,4,5 No

• Unique transitions are Gamow-Teller transitions where L~ and S~ are aligned.

KSr2I5: Homogeneous Inner Detector

• KSI has a measured light yield of 94000 photon/MeV and an energy resolution of 2.4% at 662 keV
• A two-window package was developed to hold a 7x720 mm3 rectangular parallelepiped KSI
• EC for KSI is 1080 cpd cm-3
• Analysis with KSI detector are still underway

Photo credits: Callie Goetz [6] Stand, L., Zhuravleva, M., Lindsey, A. and Melcher, C.L., 2015. Growth and characterization of potassium strontium iodide: A new high light yield scintillator with 2.4% energy resolution. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 780, pp.40-44.