Author affiliations
1
Physics Department, McGill University, Montreal, Quebec H3A 2T8, Canada
2
Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen 91058, Germany
3
Physics Department, Carleton University, Ottawa, Ontario K1S 5B6, Canada
4
Department of Physics, Duke University, and Triangle Universities Nuclear Laboratory (TUNL), Durham, North Carolina 27708, USA
5
Physics Department, University of Illinois, Urbana-Champaign, Illinois 61801, USA
6
Institute for Theoretical and Experimental Physics named by A.I. Alikhanov of National Research Centre "Kurchatov Institute", Moscow 117218, Russia
7
Department of Physics, University of South Dakota, Vermillion, South Dakota 57069, USA
8
SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
9
TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
10
Institute of High Energy Physics, Beijing 100049, China
11
Department of Physics, Laurentian University, Sudbury, Ontario P3E 2C6, Canada
12
Physics Department, Colorado State University, Fort Collins, Colorado 80523, USA
13
Department of Physics and Physical Oceanography, University of North Carolina at Wilmington, Wilmington, NC 28403, USA
14
Physics Department and CEEM, Indiana University, Bloomington, Indiana 47405, USA
15
Physics Department, Stanford University, Stanford, California 94305, USA
16
Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA
17
Amherst Center for Fundamental Interactions and Physics Department, University of Massachusetts, Amherst, MA 01003, USA
18
Technische Universität München, Physikdepartment and Excellence Cluster Universe, Garching 80805, Germany
19
Physics Department, University of Maryland, College Park, Maryland 20742, USA
20
Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USA
21
Wright Laboratory, Department of Physics, Yale University, New Haven, Connecticut 06511, USA
22
IBS Center for Underground Physics, Daejeon 34126, Korea
23
Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794, USA
24
Kellogg Lab, Caltech, Pasadena, California 91125, USA
25
LHEP, Albert Einstein Center, University of Bern, Bern, Switzerland
26
Physics Department, University of California, San Diego, La Jolla, CA 92093, USA
27
Permanent address: King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
28
Present address: Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
29
Present address: Witmem Technology Co., Ltd., No.56 BeisihuanWest Road, Beijing, China
30
Also at SNOLAB, Sudbury, ON, Canada
31
Present address: Carleton University, Ottawa, Ontario K1S 5B6,Canada
32
Deceased
33
Present address: Commissariat à l'Energie Atomique et auxénergies alternatives, France
34
Present address: University of California, Berkeley, CA, USA
35
Present address: Qventus, 295 Bernardo Ave, Suite 200, Mountain View, California 94043, USA
36
Present address: Department of Physics, University of Virginia, Charlottesville, VA 22904
37
Present address: Department of Physics at the University of California, Berkeley, California 94720, USA
38
Present address: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
39
Present address: Wright Laboratory, Department of Physics, Yale University, New Haven, Connecticut 06511, USA
40
Also at Physics Department and CEEM, Indiana University, Bloomington, IN, USA
41
Present address: Physics Department, University of California, San Diego, La Jolla, CA 92093, USA
42
Present address: SNOLAB, Sudbury, ON, Canada
43
Present address: SCIPP, University of California, Santa Cruz, CA, USA
44
Present address: Institute for Experimental Physics, Hamburg University, 22761 Hamburg, Germany
45
Present Address: Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
46
Present address: Descartes Labs, 100 North Guadalupe, Santa Fe, New Mexico 87501, USA
47
Present Address: Canon Medical Research US Inc., Vernon Hills, IL, USA
48
Present address: Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
49
Present address: Los Angeles, CA 90025, USA
50
Now a division of National Research Center "Kurchatov Institute", Moscow 123182, Russia
excited state of 136Ba is performed with the full EXO-200 dataset. A deep learning-based convolutional neural network is used to discriminate signal from background events. Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two. With the addition of the Phase II dataset taken with an upgraded detector, the median 90% confidence level half-life sensitivity of 2νββ decay to the 
state of 136Ba is 
yr using a total 136Xe exposure of 234.1 kg yr. No statistically significant evidence for 2νββ decay to the 
state is observed, leading to a lower limit of 
yr at 90% confidence level, improved by 70% relative to the current world's best constraint.