The half-life of $$^{39}$$ Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. Between 2016 and 2020, DEAP-3600 used a target mass of (3269 ± 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $$^{39}$$ Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope’s half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $$^{39}$$ Ar decays. Observing over a period of 3.4 years, the $$^{39}$$ Ar half-life is measured to be $$(302 \pm 8_\textrm{stat} \pm 6_\textrm{sys})$$ years. This new direct measurement suggests that the half-life of $$^{39}$$ Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope’s half-life as input.

Canada

P. Adhikari

R. Ajaj

Mexico

M. Alpízar-Venegas

P.A. Amaudruz

J. Anstey

D. Auty

M. Batygov

B. Beltran

M. Bigentini

C. Bina

Italy

W. Bonivento

M. Boulay

J. Bueno

M. Cadeddu

B. Cai

Spain

M. Cárdenas-Montes

S. Cavuoti

Y. Chen

Poland

S. Choudhary

B. Cleveland

R. Crampton

S. Daugherty

P. DelGobbo

P. Stefano

Russia

G. Dolganov

Germany

L. Doria

F. Duncan

M. Dunford

E. Ellingwood

A. Erlandson

S. Farahani

United Kingdom

N. Fatemighomi

G. Fiorillo

R. Ford

D. Gahan

D. Gallacher

A. Garai

P. García Abia

S. Garg

P. Giampa

A. Giménez-Alcázar

D. Goeldi

V. Golovko

P. Gorel

K. Graham

A. Grobov

A. Hallin

M. Hamstra

S. Haskins

J. Hu

J. Hucker

T. Hugues

A. Ilyasov

B. Jigmeddorj

C. Jillings

A. Joy

G. Kaur

A. Kemp

M. Khoshraftar Yazdi

M. Kuźniak

F. La Zia

United States

M. Lai

S. Langrock

B. Lehnert

J. LePage-Bourbonnais

N. Levashko

M. Lissia

L. Luzzi

I. Machulin

A. Maru

J. Mason

A. McDonald

T. McElroy

J. McLaughlin

C. Mielnichuk

L. Mirasola

A. Moharana

J. Monroe

A. Murray

C. Ng

G. Oliviéro

M. Olszewski

S. Pal

D. Papi

B. Park

M. Perry

V. Pesudo

Netherlands

T. Pollmann

F. Rad

C. Rethmeier

F. Retière

I. Rodríguez García

L. Roszkowski

R. Santorelli

F. Schuckman II

S. Seth

V. Shalamova

P. Skensved

T. Smirnova

K. Sobotkiewich

Direct measurement of the $$^{39}$$ Ar half-life from 3.4 years of data with the DEAP-3600 detector

<p>We investigate the expected precision of the reconstructed neutrino direction using a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></mrow></math>-argon quasielasticlike event topology with one muon and one proton in the final state and the reconstruction capabilities of the MicroBooNE liquid argon time projection chamber. This direction is of importance in the context of DUNE sub-GeV atmospheric oscillation studies. MicroBooNE allows for a data-driven quantification of this resolution by investigating the deviation of the reconstructed muon-proton system orientation with respect to the well-known direction of neutrinos originating from the Booster Neutrino Beam with an exposure of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.3</mn><mo>×</mo><msup><mn>10</mn><mn>21</mn></msup></math> protons on target. Using simulation studies, we derive the expected sub-GeV DUNE atmospheric-neutrino reconstructed simulated spectrum by developing a reweighting scheme as a function of the true neutrino energy. We further report flux-integrated single- and double-differential cross section measurements of charged-current <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>μ</mi></msub></math> quasielasticlike scattering on argon as a function of the muon-proton system angle using the full MicroBooNE data sets. We also demonstrate the sensitivity of these results to nuclear effects and final state hadronic reinteraction modeling.</p>

P. Abratenko

D. Andrade Aldana

L. Arellano

J. Asaadi

Israel

A. Ashkenazi

S. Balasubramanian

B. Baller

A. Barnard

G. Barr

D. Barrow

J. Barrow

V. Basque

J. Bateman

O. Benevides Rodrigues

S. Berkman

A. Bhat

M. Bhattacharya

M. Bishai

A. Blake

B. Bogart

T. Bolton

M.B. Brunetti

L. Camilleri

D. Caratelli

F. Cavanna

G. Cerati

A. Chappell

J.M. Conrad

M. Convery

L. Cooper-Troendle

J.I. Crespo-Anadón

R. Cross

M. Del Tutto

S.R. Dennis

P. Detje

Switzerland

R. Diurba

Z. Djurcic

K. Duffy

S. Dytman

B. Eberly

P. Englezos

A. Ereditato

J.J. Evans

C. Fang

W. Foreman

B.T. Fleming

D. Franco

A.P. Furmanski

F. Gao

D. Garcia-Gamez

S. Gardiner

G. Ge

S. Gollapinni

E. Gramellini

P. Green

H. Greenlee

L. Gu

W. Gu

R. Guenette

P. Guzowski

L. Hagaman

M.D. Handley

O. Hen

C. Hilgenberg

G.A. Horton-Smith

A. Hussain

B. Irwin

M.S. Ismail

C. James

China

X. Ji

J.H. Jo

R.A. Johnson

D. Kalra

G. Karagiorgi

W. Ketchum

M. Kirby

T. Kobilarcik

N. Lane

J.Y. Li

Y. Li

K. Lin

B.R. Littlejohn

L. Liu

W.C. Louis

X. Luo

First study of neutrino angle reconstruction using quasielasticlike interactions in MicroBooNE