neutrinoless double beta decay - 2025 ACF Winter

Question

Observation of this process would confirm the existence of elementary Majorana (“ma-yo-RA-na”) fermions. For 10 points each:

[10h] Name this type of nuclear decay that emits only two electrons but also violates lepton number.

ANSWER: neutrinoless double beta decay [prompt on double beta decay]

[10m] The nEXO experiment plans to measure neutrinoless double beta decay in liquid xenon-136 via this process, in which ionization radiation is absorbed by a material and then re-emitted as light.

ANSWER: scintillation [accept scintillators]

[10e] Experiments observing neutrinoless double beta decay also serve to bound this physical quantity for neutrinos, which is less than one electronvolt, or 1.782 times 10 to the negative 36 kilograms.

ANSWER: mass

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Summary


California	Main	Y	4	10.00	100%	0%	0%
Canada	Main	Y	6	10.00	83%	0%	17%
Lower Mid-Atlantic	Main	Y	4	12.50	100%	0%	25%
Midwest	Main	Y	6	13.33	100%	17%	17%
North	Main	Y	8	11.25	100%	0%	13%
Northeast	Main	Y	1	20.00	100%	100%	0%
Pacific Northwest	Main	Y	8	10.00	88%	0%	13%
Pacific Northwest	Main	Y	1	10.00	100%	0%	0%
South Central	Main	Y	4	10.00	100%	0%	0%
Southeast	Main	Y	8	8.75	88%	0%	0%
UK	Main	Y	4	12.50	100%	0%	25%
Upper Mid-Atlantic	Main	Y	7	10.00	86%	0%	14%
Upstate NY	Main	Y	7	10.00	100%	0%	0%
2025 ACF Nationals	2025-08-09	Y	8	15.00	100%	38%	13%
2024 ARCADIA at UC Berkeley	04/19/2025	Y	3	13.33	100%	33%	0%

Data


Berkeley A	Berkeley D	0	0	10	10
Berkeley C	Berkeley F	0	0	10	10
Stanford A	Berkeley B	0	0	10	10
Stanford C	Berkeley E	0	0	10	10
Claremont Scripps	UCSD Two Running Violet V Forms	0	0	10	10
UCLA D	UCI	10	0	10	20
UCLA A	UCSB	0	0	10	10
UCSD Vices and Virtues	UCLA B	0	0	10	10
UCSD What Hath God Wrought	UCLA C	0	0	0	0
USC	Claremont Pitzer	0	0	10	10
CWRU A	MSU A	0	0	10	10
CWRU B	OSU D	0	0	10	10
MSU B	OSU B	0	0	10	10
OSU C	OSU A	10	0	10	20
Clemson B	Tennessee A	0	0	10	10
Liberty A	Tennessee B	0	0	10	10
Tusculum	South Carolina A	0	0	10	10
Virginia A	NC State	0	10	10	20
North Carolina A	South Carolina B	10	0	10	20
Liberty B	Virginia Tech B	0	0	10	10
Johns Hopkins C	George Washington A	0	0	10	10
Georgetown A	George Mason B	0	0	10	10
Maryland C	Georgetown B	0	0	10	10
Maryland B	Penn A	0	0	10	10
NYU A	Catholic University	10	0	10	20
NYU B	George Washington B	0	0	10	10
Johns Hopkins A	Notre Dame E	0	0	10	10
Columbia A	Princeton A	0	10	10	20
Michigan A	Chicago D	0	0	10	10
Indiana A	Purdue C	10	0	10	20
Illinois A	Indiana B	0	0	10	10
Michigan B	Louisville B	0	0	10	10
Michigan D	Chicago A	0	0	10	10
Notre Dame D	Kentucky	0	0	0	0
Purdue A	Illinois B	0	0	10	10
Purdue B	Notre Dame A	0	0	10	10
Chicago C	Notre Dame C	0	0	10	10
Maryland A	George Mason C	0	0	10	10
Minnesota C	Carleton	0	0	10	10
Iowa State	Macalester B	0	0	10	10
St. Thomas	Nebraska	0	0	10	10
Brown A	BC A	0	0	10	10
Yale A	Brandeis Clemenceau	0	0	10	10
Amherst A	Brown C	0	0	10	10
Brown B	MIT A	0	0	10	10
MIT B	Dartmouth	0	0	10	10
Tufts B	Brandeis Wilson	0	0	10	10
Williams	Bowdoin A	0	0	0	0
Harvard	Yale B	0	0	10	10
British Columbia A	Washington B	0	0	10	10
Washington A	British Columbia D	0	0	10	10
Simon Fraser	British Columbia C	10	0	10	20
Alberta	British Columbia B	0	0	10	10
Alberta B	UTD A	0	0	10	10
Arizona State A	Northwestern B	0	0	10	10
Northwestern A	Arizona State B	10	0	10	20
Ohio	Tulsa	0	0	0	0
Iowa	Rose State	0	0	10	10
Georgia Tech A	Alabama A	0	0	10	10
Auburn A	Georgia Tech B	0	0	10	10
Georgia Tech C	Alabama B	0	0	10	10
Vanderbilt B	Georgia Tech D	0	0	10	10
Huntsville A	Vanderbilt A	0	0	10	10
Bruin A	Huntsville B	0	0	10	10
UAB A	Auburn B	0	0	10	10
Birmingham A	Sheffield B	0	0	10	10
Imperial A	Cambridge B	0	10	10	20
LSE A	Cambridge C	0	0	10	10
Warwick B	Edinburgh B	0	0	10	10
Imperial B	Edinburgh A	10	0	10	20
Bristol A	LSE B	0	10	10	20
Manchester A	Southampton A	0	0	10	10
Cambridge A	Manchester B	0	10	10	20
ESF	Cornell-DII	0	0	10	10
Texas A	McGill D	0	0	10	10
Northwestern C	Texas B	0	0	10	10
Minnesota A	Macalester A	0	0	10	10
RIT A	Rochester	0	0	10	10
Binghamton B	RIT B	0	10	10	20