Zooming in on Axions

The latest results from a search for QCD axions from the Sun as well as axion-like particles of solar and dark matter origins were presented by Dr. Michelle Galloway from the University of Zurich on June 26th at the “Zooming in on Axions in the Early Universe” workshop hosted by CERN. With an unprecedented low background of 76 ± 2 stat events/(tonne × year × keV) between 1–30 keV, XENON1T is uniquely poised to explore new parameter space for these electronic-recoil channels via the axio-electric effect. Our search revealed an excess of events in the (1 – 7) keV region, favoring these channels over background with significances of 3.5 sigma for solar axions/ALPs and 3.0 sigma global (4.0 local) for ALP dark matter with a peak at 2.3 +- 0.2 keV (68% C.L.). The talk reviewed the detection principles, cross checks of our results, discrepancy with stellar constraints, and presented a hypothesis of a new background from a previously undetected tritium component. Presentation materials can be found here.


XENON1T S2-only Data Release

Today, XENON releases data from the XENON1T S2-only / light dark matter search published in Physical Review Letters 123, 251801 (2019). You can find the data release at:

This includes observed events, background models, and response matrices to construct arbitrary signal models. Together, these allow researchers to constrain their own dark matter models using the XENON1T S2-only data. We included a jupyter notebook example to help you get started.

We look forward to seeing what models the community will think of!

XENON at the 2019 Swiss-Austrian Physical Society Meeting

Five members of the University of Zurich group participated at the 2019 Swiss-Austrian Physical Society Meeting in Zurich, Switzerland.

Adam Brown contributed with a poster on the XENONnT upgrades and status and Ricardo Peres on the software for the supernova early warning system:

Giovanni Volta, Michelle Galloway and Chiara Capelli contributed with talks on the general XENON1T results, the ongoing search for dark absorption and the analysis on high energy events respectively. The full talks are linked. Below a key slide from each talk is shown: the spin-independent elastic WIMP-nucleon scattering limit at 90% CL still are the most sensitive limits on WIMP dark matter. The motivation for light dark matter searches is becoming more and more pressing. And our reconstruction of single-site and multiple-site interactions for the neutrinoless double beta decay search significantly improves our capability to contribute to this exciting science channel.

Talk at Lepton Photon 2019

A talk on the measurement of the double electron capture half-life of xenon-124 with the XENON1T experiment was given at the Lepton Photon 2019 conference in Toronto in August 2019. Ethan Brown from Rensselaer Polytechnic Institute presented this exciting result, demonstrating the power of the ultra-low background in XENON1T. This yielded the measurement of the longest process ever directly observed at 1.8×10^22 years, a trillion times longer than the age of the Universe.

Some of the dark matter search results were also presented in this talk, advertising the incredible success of the XENON program and the science reach of the XENON1T experiment in rare event detection.


XENON was on the agenda at the European Physical Society Conference on High Energy Physics 2019 (EPS-HEP2019), which was held in Ghent, Belgium in the middle of July. The talk, presented by Adam Brown from the University of Zurich group, concentrated on results from XENON1T and also provided an overview of the work which is well underway to build the next generation detector, XENONnT.

Among results shown were our searches for elastic WIMP scattering and the recently published observation of double electron capture in 124Xe. The slides can be downloaded here. While the XENONnT upgrade currently in progress at Gran Sasso features many improvements of the XENON1T detector, Adam summarized four major improvements in one colorful slide.

XENON talk at Patras Workshop

A talk on the XENON project was given at the 15th Patras Workshop on Axions, WIMPs and WISPs, which was held in Freiburg (Germany) in the first week of June. Andrea Molinario from the Gran Sasso Science Institute and Laboratori Nazionali del Gran Sasso presented the most recent results from the data analysis of XENON1T, in particular the search for WIMP-nucleon spin-dependent and spin-independent interactions. The sensitivity of this search will be much-improved upon by the upcoming XENONnT phase of the experiment.

The first observation of 124Xe double electron capture and the measurement of the half-life of the process were also shown (this topic had a dedicated talk by Sebastian Lindemann). In the second part of his talk, Andrea gave an update on the status of XENONnT. The presentation is available here.

XENON1T talk at Low Radioactivity Technique 2019

Our latest XENON1T paper on details of our analysis was presented at the Low Radioactivity Techniques, a conference focused on low background experiments. In the talk (that you can find here), the response model of the detector, the challenges of background modeling, as well as the used techniques were described. In a low background experiment is often hard to asses the expected distribution of events due to lack of statistics and to many subtle effects. In the talk a novel technique was described to introduce a well-motivated systematic uncertainty to the background model based on a calibration sample, which can be relevant to other low background experiments.

XENON on skis

XENON was present at the ALPS conference in Austria. Chiara Capelli from University of Zurich gave a talk on behalf of the XENON collaboration. The talk focused on the latest XENON1T results on spin-independent and spin-dependent WIMPs, and on the newest results on two-neutrinos double electron capture, with a final status on the XENONnT upgrade. The talk is available here.

On March 8, 2019, Shigetaka Moriyama presented the status of the XENONnT experiment at the international symposium on “Revealing the history of the Universe with underground particle and nuclear research” in Sendai, Japan. The symposium is held by a Japanese research community working on underground experiments and developing low background techniques. Its members are interested in the physics goals of XENONnT as well as its radon reduction technique and will enhance the experiment with Super-Kamiokande’s water Cherenkov technology developed in Kamioka, Japan, for the SK-Gd project. Super-Kamiokande developed this technology to measure the diffuse relic neutrino flux from past supernovae.

At the Sendai meeting, this community is summarizing its achievements over last five years and aims to secure new funding for the next five years by expanding its activity through internationalization and the inclusion of new physics topics such as history of stars, galaxies, and the origin of the heavy elements in the Universe.

Its HP is here and the slides are available here.

Outline the XENONnT Computing Scheme at the 2nd Rucio Community Workshop in Oslo

Oslo welcomed all 66 participants of the second Rucio Community Workshop with pleasant weather and a venue which offered an astonishing view about the capital of Norway.
The opensource and contribution model of the Rucio data management tool captures more and more attention from numerous fields. Therefore, 21 communities reported this year about the implementation of Rucio in their current data workflows, discussed with the Rucio developing team possible improvements and chatted among each other during the coffee breaks to learn from others experiences. Among the various communities were presentations given by the DUNE experiment, Belle-2 and LSST. The XENON Dark Matter Collaboration presented the computing scheme of the upcoming XENONnT experiment. Two keynote talks from Richard Hughes-Jones (University of Maryland) and Gundmund Høst (NeIC) highlighted the concepts of the upcoming generation of academic networks and the Nordic e-Infrastructure Collaboration.

After the successful XENON1T stage with two major science runs, a world-leading limit for spin-indepenent Dark Matter interactions with nucleons and further publications, the XENON1T experiment stopped data taking in December 2018. We aim for two major updates for the successor stage of XENONnT: a larger time projection chamber (TPC) which holds ~8,000 kg of liquid xenon with 496 PMTs for signal readout and an additional neutron veto detector based on Gadolinium doped water in our water tank. That requires upgrades in our current data management and processing scheme, which was presented last year at the first Rucio Community Workshop. Fundamental change is the new data processor STRAX which allows us much faster data processing. Based on the recorded raw data, the final data product will be available at distinct intermediate processing stages which depend on each other. Therefore, we stop using our “classical” data scheme of raw data, processed data and minitrees, and instead aim for a more flexible data structure. Nevertheless, all stages of the data are distributed with Rucio to connected grid computing facilities. STRAX will be able to process data from the TPC, the MuonVeto and the NeutronVeto together to allow coincident analysis.

The data flow of the XENONnT experiment

The data flow of the XENONnT experiment. A first set data is processed already at the LNGS. All data kinds are distributed with Rucio to the analysts.

Reprocessing campaigns are planed ahead with HTCondor and DAGMan jobs at EGI and OSG similar to the setup of XENON1T. Due to the faster data processor, it becomes necessary to outline a well-established read and write routine with Rucio to guarantee quick data access.
Another major update in the XENONnT computing scheme becomes the tape backup location. Because of the increased number of disks and tape allocations in the Rucio catalogue, we will abandon the Rucio independent tape backup in Stockholm and use dedicated Rucio storage elements for storing the raw data. The XENON1T experiment collected ~780 TB of (raw) data during its life time which are all managed by Rucio. The XENON Collaboration is looking forward to continuing this success story with XENONnT