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Neutrinoless double beta decay search in Xe - next-generation experiment workshop

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Thomson House Ballroom (Montreal)

Thomson House Ballroom

Montreal

Thomson House 3650 McTavish St Montreal, QC H3A 1X1
Roxanne Guenette (University of Manchester), Thomas Brunner (McGill and TRIUMF)
Description
The search for neutrinoless double beta decay, ideally in more than one isotope, has been identified as high priority by the international subatomic physics community. Over the past decades, significant advancements have been made in the development of xenon TPCs.

Proposed next-generation experiments intend to deploy tonne(s) of the double beta decaying isotope Xe-136 and are expected to reach sensitivities in the mid-10^27 to 10^28 years range. The complexity of these experiments and the cost of xenon likely will limit the number of next-generation experiments and their timescales.

We are organizing a workshop to discuss possibilities and opportunities for a coherent collaborative effort to search for neutrinoless double beta decay in Xe-136. We want to keep this workshop as inclusive and as broad as possible and are inviting possible collaborators with the aim of creating a new consortium or collaboration under a new name with the broad goal of developing a roadmap for a competitive search for neutrinoless double beta decay using xenon as a target medium.

The workshop will be held November 12-14, 2025 in Montreal. 

Thomson House Ballroom
3650 McTavish St
Montreal, QC H3A 1X1

All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 

Organizing committee:
Thomas Brunner
Roxanne Guenette
Mike Heffner
Ben Jones
Justo Martin-Albo
Fran Spidle

With the kind sponsorship from:

                  

              

 

and with entertainment by Les Restants d’Cabane:

Registration
Registration Information Next Gen Xe workshop
Register
Participants
  • Ako Jamil
  • Alex Todd
  • Alex Wright
  • Amelia Remnant
  • Andrea Pocar
  • ANKIT GAUR
  • Annika Lennarz
  • Antoine Amy
  • Art McDonald
  • Ben Jones
  • Bill Fairbank
  • Brais Palmeiro Pazos
  • Brian Lenardo
  • Brian Mong
  • Caio Licciardi
  • Chloé Malbrunot
  • Christine Kraus
  • Daniel Akerib
  • Darren Grant
  • Dave Hawkins
  • David Asner
  • David Gallacher
  • David Moore
  • David Sinclair
  • Eleanor Allen
  • Eric Church
  • Eric Dahl
  • Erica Caden
  • Ethan Coulthard
  • Fabrice Retiere
  • Fran Spidle
  • Francesc Monrabal Capilla
  • Frédéric Girard
  • Gabriel Orebi Gann
  • Giorgio Gratta
  • Guillaume Giroux
  • Hossein Rashidi
  • Hugh Lippincott
  • Hussain Rasiwala
  • Irina Nitu
  • Isaac Arnquist
  • Jason Holt
  • Jessica Provenz
  • Jianglai Liu
  • Joaquim Palacio Navarro
  • Jodi Cooley
  • Jose Angel Hernando Morata
  • Jose F. Toledo
  • Juan Jose Gomez Cadenas
  • Julien Masbou
  • Justo Martín-Albo
  • Kaixuan Ni
  • Kevin Gracequist
  • Krishan Mistry
  • Krishna Kumar
  • Kyle Leach
  • Liang Yang
  • Lucas Darroch
  • Michela Lai
  • Michelle Dolinski
  • mike heffner
  • Naman Walia
  • Nasim Fatemighomi
  • Nigel Smith
  • Pablo Herrero Gomez
  • Pau Novella
  • Raheema Hafeji
  • Ray Bunker
  • Regan Ross
  • Richard Saldanha
  • Rituparna Kanungo
  • Riya Rai
  • Roxanne Guenette
  • Samin Majidi
  • Samuele Sangiorgio
  • Sean Paling
  • Simon Lavoie
  • Simon Viel
  • Spencer Axani
  • Stefano Roberto Soleti
  • Stephen Sekula
  • Tania Atoui
  • Teena Vallivilayil John
  • Thomas Brunner
  • Tim Daniels
  • Tony Noble
  • Tsvetelin Totev
  • Zepeng Li
Contact
  • Wednesday, 12 November
    • 08:30 → 09:00
      Pre-Registration All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 

      All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 
    • 09:00 → 10:00
      Introduction, goals and context (Chair: Hugh Lippincott)

      Chair: Hugh Lippincott

    • 10:00 → 10:30
      Break - At the venue - light food and drink provided 30m
    • 10:30 → 12:00
      Status of the field (Chair: Michelle Dolinski)

      Chair: Michelle Dolinski

    • 12:00 → 13:30
      Lunch - provided 1h 30m

      soup, sandwich and salad options

    • 13:30 → 15:00
      Theory discussions of 0nbb: (Chair: Liang Yang)
    • 15:00 → 15:30
      Break 30m
    • 15:30 → 16:30
      Technical challenges and new ideas: (Chair: Nigel Smith)
    • 16:30 → 17:54
      Blue Sky Session: (Chair: Nigel Smith)
      • 16:30
        Shielding and Outer Detectors 14m

        Cosmogenic muons are a major background source in rare event search experiments. To mitigate this background, neutrinoless double beta decay ($0\nu\beta\beta$) and direct detection dark matter experiments prefer to operate in deep underground laboratories, where they can receive adequate shielding from cosmic rays. However, high energy muons can still reach underground and create backgrounds for these experiments. To reduce such cosmogenic muon backgrounds, the rare-event search experiments deploy an outer detector to tag the muons. The outer detector can act as a muon veto. An active muon veto detects light produced either via Cherenkov radiation (if the detector is filled with the water) or scintillation light (if the detector is filled with the scintillation medium). The outer detector is instrumented with photon detection modules, such as photomultiplier tubes (PMTs) or silicon photo multipliers (SiPM). In addition, the outer detector can also serve as passive shielding, moderating secondary neutrons produced by muon interactions. In this talk, I will discuss about requirements of the deep underground laboratories, and the specifications of the outer detectors for the current and future rare event search experiments.

        Speaker: Dr Teena Vallivilayil John (Postdoc)
        Shielding and Outer Detectors.pdf
      • 16:44
        What is the limit of topological background rejection with a gas TPC? 14m

        Gaseous xenon time projection chambers (GXeTPC) are an excellent detector technology for reducing radiogenic backgrounds in $0\nu\beta\beta$ decay searches due to the extended beta tracks. The signal consists of two emitted beta electrons with 2.45 MeV of energy, and their track lengths scale inversely with the gas pressure, reaching ~2 m in size for 1 bar of gas pressure or ~20 cm at 10 bar. The most significant backgrounds that can mimic this signature are gamma rays originating from radiogenic sources or beta decays from cosmogenically activated isotopes such as Xe-137. Such backgrounds generally produce a single electron signature, and GXeTPCs can reject a significant fraction of them using the amount of energy deposition near the track ends and event multiplicities. In this talk, I will be discussing how GXeTPCs can best use the topological information to reject these backgrounds, including the use of new variables that exploit the angular information of the tracks, and what factors can limit this.

        Speaker: Dr Krishan Mistry (University of Texas at Arlington)
        GasTPCTopo_Mistry.pdf
      • 16:58
        Are five tonnes of xenon enough? 14m

        Target mass is a key consideration in optimizing the design of a future neutrinoless double beta decay detector with xenon.  This short talk makes the case that in the current context, to achieve our scientific goals, a target mass larger than 5 tonnes needs to be considered seriously.

        Speaker: Dr Simon Viel (Carleton University)
        sviel_0vbb_nov12.pdf
      • 17:12
        Reaching the Normal Hierarchy for double beta decay 14m

        To reach the Normal Hierarchy and thus definitively address the question of lepton number conservation, current background levels must be reduced by a factor of ~1000 and some of this must come from improved energy resolution. I suggest this might be achieved in liquid xenon by a series of fundamental changes in design to include (a) the use of low IP additives such as TEA to allow much higher detection efficiency together with charge and light measurements on each charge cluster, (b) the use of fine pixelated detectors, (c) positive ion detection to reduce diffusion and preserve electron track information and (d) improved high voltage design to allow operation at higher fields. Work on this should be done globally with the aim of a global detector approach.

        Speaker: Dr David Sinclair (Carleton University)
        Sinclair-McGill workshop.pptx
      • 17:26
        X/Y multi-site reconstruction in dual-phase xenon detectors 14m

        In liquid xenon detectors searching for neutrinoless double beta decay (0vbb), single-site/multi-site (SS/MS) discrimination is critical for reducing backgrounds from 214Bi gamma rays. Dual-phase detectors, which utilize electroluminescence to measure the ionization signals, have demonstrated excellent multi-site identification in the longitudinal (z) direction but have not demonstrated SS/MS discrimination in the transverse (x/y) plane. If multi-site interactions could be identified down to separations of a few mm, 214Bi backgrounds could be reduced by a factor of two, potentially increasing the sensitivity of dual-phase detectors to 0vbb by up to ~50%. I will discuss the capability and limitations of x/y SS/MS discrimination in dual-phase detectors with the traditional electroluminescence readout, and introduce the possibility of adding additional wire grids to such detectors to improve spatial reconstruction via induction sensing.

        Speaker: Dr Brian Lenardo (SLAC)
        McGill 0vbb workshop - Nov 12, 2025 - X_Y multi-site reconstruction in dual-phase xenon detectors.pdf
      • 17:40
        A journey to ITACA 7m

        High-pressure gaseous xenon time projection chambers with electroluminescence (HGXeTPC-EL), are among the leading technologies for the search of neutrinoless double beta decay. Their combination of excellent energy resolution and detailed topological reconstruction enables powerful discrimination between single-electron and double-electron tracks, the latter representing the characteristic signature of a $0\nu\beta\beta$ event near the decay energy. Background suppression in these detectors relies critically on this topological information, but its effectiveness is ultimately limited by the diffusion of drifting electrons and by the spatial blurring introduced during electroluminescent amplification.

        Traditional approaches to mitigate diffusion, such as the addition of molecular cooling agents (e.g., CO$_2$, CH$_4$), are constrained by their strong quenching of xenon scintillation and electroluminescence. To overcome these limitations, we introduce ITACA (Ion Tracking with Ammonium Cations Apparatus), a novel concept that exploits both the prompt electron track and a delayed ion track to enhance event reconstruction. In this scheme, trace amounts of NH$_3$ (at ppb levels) convert xenon ions (Xe$^+$) into ammonium ions (NH$_4^+$) without affecting scintillation or EL yields. Electrons drift to the anode within milliseconds, forming the conventional EL image, while NH$_4^+$ ions drift slowly toward the cathode on a timescale of seconds. Using the primary scintillation (S1) signal as a timing reference, an electrostatic gate releases the ion cloud onto a sensor array of molecular detectors, which can be optically interrogated to reconstruct the ion track with sub-millimeter diffusion and without EL smearing.

        By combining the electron and ion images, ITACA could significantly improve the topological background rejection of xenon TPCs, potentially by an order of magnitude. The applicability of this technique to liquid xenon detectors is also discussed, though the higher density and reduced track length in the liquid phase make ion tracking less practical in that regime.

        Speaker: Dr Roberto Soleti
        itaca.pdf
    • 19:00 → 21:30
      Workshop Dinner - Restaurant Hà - 600 Rue William 2h 30m Restaurant Hà

      Restaurant Hà

      600 Rue William Montréal, QC, H3C 1N6
  • Thursday, 13 November
    • 08:30 → 09:00
      Pre-registration All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 

      All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 
    • 09:00 → 10:00
      Lessons learned and plans for 0nbb: (Chair: Brian Mong)
      • 09:00
        Lessons learned from the formation of XLZD 20m
        Speaker: Dr Kim Palladino
        LessonsLearnedOnTheWaytoXLZD.pdf
      • 09:20
        Lessons learned from Global Argon Dark Matter 20m
        Speaker: Dr Jocelyn Monroe
      • 09:40
        Lessons learned from Dune and building in the current context 20m
        Speaker: Dr Mary Bishai
    • 10:00 → 10:30
      Break - at the venue - light food and drink provided 30m
    • 10:30 → 12:30
      Technical Challenges 2: (Chair: Jose Angel)
    • 12:30 → 14:00
      Lunch - provided 1h 30m

      at venue

    • 14:00 → 15:30
      Technical Challenges 2: (Chair: Bill Fairbank)
    • 15:30 → 15:50
      Break - at the venue - light food and drink provided 20m
    • 15:50 → 17:45
      Panel discussion on best strategy for Xenon experiments (Chair: Brian Lenardo)
      • 15:50
        Joint oversight committee talk 30m
        Speaker: Dr Nigel Smith
        2025-11-13 Xenon Workshop-1.pdf
      • 16:20
        Panel on best strategy for Xe experiments 1h 15m

        Moderator: Dr. Art McDonald
        Panelists:
        Dr. Jodi Cooley
        Dr. Juan José Gómez Cadenas
        Dr. Dan Akerib
        Dr. Krisha Kumar
        Dr. Sean Pauling

        Speakers: Dr Art McDonald - Moderator, Dr Dan Akerib, Dr Jodi Cooley, Juan José Gómez Cadenas, Krishna Kumar, Sean Pauling
    • 17:45 → 19:45
      Les Restants d’Cabane at Thomson House 2h first floor (Thomson house)

      first floor

      Thomson house

      First floor

      Quebecois band - first floor of Thomson house. Hors d'oeuvres will be served

  • Friday, 14 November
    • 08:30 → 09:00
      Preregistration 30m All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 

      All zoom sessions: https://mcgill.zoom.us/my/xe0vbbws 
    • 09:00 → 10:30
      Xe detector technologies: (Chair: Dan Akerib)
    • 10:30 → 11:00
      Break - at the venue - light food and drink provided 30m

      at venue

    • 11:00 → 13:00
      Session 10: Where to go from here? (Chair: Stephen Sekula)
      • 11:00
        Other technologies 30m

        KamLAND2-ZEN, THEIA, LAR+Xe, and others

        Speaker: Dr Gabriel Orebi
        20251114 XeDBD.pdf
      • 11:30
        Quo Vadis 1h

        Where do we want to go? Can we develop a consortium? How would we do this?

        Speaker: Dr Ben Jones (UTA)
        0nubbXeTalk.pdf
      • 12:30
        Workshop summary and wrap-up 30m
        Speaker: Dr Thomas Brunner (McGill U)
        20251114-Xe-0vBB-end-red.pdf
    • 13:00 → 14:00
      Lunch - provided 1h

      Lunch and end of workshop

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