The XENON phased program

The XENON Dark Matter Direct Search Experiment aims to directly detect the fraction of dark matter in the Universe. The particles sustaining the existence of dark matter are known as WIMPs (Weakly Interactive Massive Particles). The existing models predict interaction rates with regular matter that can be as low as 1 event/ton Xe/year. This way large detection volumes are needed and extreme care is needed with the background radiation levels.
A double phase, liquid and gas, xenon detector is proposed to detect WIMP. The XENON detection principle is based in the detection of primary scintillation (liquid phase) and secondary scintillation (gas phase) induced by the energy deposited by a WIMP interaction in xenon.
XENON10 was the first detector developed for WIMP detection, starting its operation in 2006. The results obtained settled new exclusions limits in the WIMP-nucleon cross section for spin-independent interaction (Phys. Rev. Lett. 100 (2008) 21303).
Since 2008, XENON100, a detector with a 10 fold larger target mass, is acquiring data. With active xenon shielding contributing to a drastically reduced radioactive background activity level plus an increased scintillation efficiency detection, XENON100 consistently delivered the best exclusion limits in dark matter search (Phys. Rev. Lett. 107 (2011) 131302; Phys. Rev. Lett., 109 (2012) 181301; Phys. Rev. Lett., 111 (2013) 021301), and attained its projected sensitivity in 2012.
In 2013 a new phase started with the construction of XENON1T, a 20 fold larger target mass detector than XENON100. With an additional two hundred fold reduction on the background levels XENON1T. It started taking data in 2016 and the WIMP sensitivity limit (two orders of magnitude below the one set by XENON100) was reached after 2 years of operation, keeping the world lead in the dark matter search efforts.
XENONnT construction started in 2018 and is currently acquiring science data. This final step of the program with an over 8 tons ultrapure xenon target will lead the way with the best prospects ever for dark matter detection.
Real-time news on the XENONnT progress can be followed in xenonnt.org

Latest results

March 22, 2023
First WIMP Search Results from the XENONnT Experiment

The XENON collaboration presented today results from XENONnT, the latest-generation experiment of the XENON Dark Matter project dedicated to the direct search for Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs). With an initial exposure slightly larger than 1 tonne x year, a blind analysis shows that the data is consistent with the expectations from the background-only hypothesis. XENONnT thus sets new limits on interaction of WIMPs with ordinary matter. Thanks to the five times lower background, XENONnT improved on the results from the former XENON1T experiment obtained with a similar exposure. An article has been submitted to Physical Review Letters, and its preprint is available at the XENON website (https://xenonexperiment.org/).

Experiments searching for dark matter require the lowest possible level of natural radioactivity, both from sources intrinsically present in the liquid xenon target and from construction materials and the environment. The former is dominated by radon atoms that are constantly emitted from detector materials and which are extremely difficult to reduce. The XENON collaboration has pioneered the technologies to lower radon to an unprecedented low level, from extensive material selection campaigns to an online cryogenic distillation system that actively removes radon from the xenon. Another important radioactive background comes from neutrons that are generated by the radioactivity of detector materials. In XENONnT, its impact has been reduced by a novel neutron veto detector installed inside the water tank around the xenon cryostat, which allows for recognition and removal of those neutron events that can otherwise mimic the WIMP signature. The XENONnT detector is so sensitive to rare interactions that even neutrinos, the most elusive particles known so far, have to be considered in the background model.

With this result, XENONnT strengthens previous constraints already with a first short exposure.

TXENONnT is collecting more data, with improved detector conditions and an even lower background level due to a further improvement of the radon control and online removal system, aiming for an increased WIMP sensitivity over the following years.

More information on the XENON project can be found at https://xenonexperiment.org/

Team Members

Current Coimbra XENON team:

Former Coimbra XENON team:

Collaboration

Institutes involved in the XENON Project:











Publications

  • Material radiopurity control in the XENONnT experiment, E. Aprile et al. , Eur. Phys. J. C 82 (2022) 599
  • Application and modeling of an online distillation method to reduce krypton and argon in XENON1T , E. Aprile et al., Progress of Theoretical and Experimental Physics, (2022) 053H01
  • The Xenon Road to Direct Detection of Dark Matter at LNGS: The XENON Project, Pietro Di Gangi on behalf of the XENON Collaboration, Universe, 7 (2021)313
  • 222Rn emanation measurements for the XENON1T experiment, E. Aprile et al., Eur. Phys. J. C 81 (2021) 337
  • Search for inelastic scattering of WIMP dark matter in XENON1T, E. Aprile et al., Phys. Rev. D 103(2021) 063028
  • Search for Coherent Elastic Scattering of Solar 8B Neutrinos in the XENON1T Dark Matter Experiment, E. Aprile et al., Phys. Rev. Lett. 126 (2021) 091301
  • Projected WIMP sensitivity of the XENONnT dark matter experiment, E. Aprile et al., JCAP 11 (2020) 031
  • Excess electronic recoil events in XENON1T, E. Aprile et al., Phys. Rev. D 102 (2020) 072004
  • Energy resolution and linearity of XENON1T in the MeV energy range, E. Aprile et al., European Physical Journal C 80 (2020) 785
  • Results of the 1 tonne x year WIMP search with XENON1T, P. Di Gangi et al., Nuovo Cimento C 42 (2019) 76
  • Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T, E. Aprile et al., Phys. Rev. Lett. 123 (2019) 241803
  • Light Dark Matter Search with Ionization Signals in XENON1T, E. Aprile et al. Phys. Rev. Lett. 123 (2019) 251801
  • XENON1T dark matter data analysis: signal reconstruction, calibration, and event selection, E. Aprile et al., Phys. Rev. D 100 (2019) 052014
  • The XENON1T data acquisition system, E. Aprile et al., JINST (2019) P07016
  • XENON1T dark matter data analysis: signal and background models and statistical inference, E. Aprile et al., Phys. Rev. D 99 (2019) 112009
  • Measurement of electron multiplication and ionization coefficients in high-pressure xenon,H. Kusano, J.A.M. Lopes e N. Hasebe, Nucl. Instr. Meth. A 937 (2019) 53
  • Observation of two-neutrino double electron capture in 124Xe with XENON1T, E. Aprile et al., Nature 568 (2019) 532
  • First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment, E. Aprile et al., Phys. Rev. Lett. 122 (2019) 071301
  • Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T, E. Aprile et al., Phys. Rev. Lett. 122 (2019) 141301
  • Dark Matter Search Results from a One Ton-Year Exposure of XENON1T, E. Aprile et al., Phys. Rev. Lett. 121 (2018) 111302
  • Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon, E. Aprile et al., Phys. Rev. D 97 (2018) 092007
  • Intrinsic backgrounds from Rn and Kr in the XENON100 experiment, E. Aprile et al., Eur. Phys. J. C 78 (2018) 132
  • Material radioassay and selection for the XENON1T dark matter experiment, E. Aprile et al., Eur. Phys. J. C 77 (2017) 890
  • The XENON1T dark matter experiment, E. Aprile et al., Eur. Phys. J. C 77 (2017) 881
  • Search for bosonic super-WIMP interactions with the XENON100 experiment, E. Aprile et al., Phys. Rev. D 96 (2017) 122002
  • First Dark Matter Results from the XENON1T Experiment, E. Aprile et al., Phys. Rev. Lett. 119 (2017) 181301
  • Search for magnetic inelastic dark matter with XENON100, E. Aprile et al., Phys. Rev. JCAP 10 (2017) 039
  • Effective field theory search for high-energy nuclear recoils using the XENON100 dark matter detector, E. Aprile et al., Phys. Rev. D 96 (2017) 042004
  • Search for WIMP inelastic scattering off xenon nuclei with XENON100, E. Aprile et al., Phys. Rev. D 96 (2017) 022008
  • Online Rn-222 removal by cryogenic distillation in the XENON100 experiment, E. Aprile et al., Eur. Phys. J. C 77 (2017) ͘358
  • Removing krypton from xenon by cryogenic distillation to the ppq level, E. Aprile et al., Eur. Phys. J. C 77 (2017) ͘358
  • Results from a calibration of XENON100 using a source of dissolved radon-220, E. Aprile et al., Phys. Rev. D 95 (2017) 072008
  • Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data, E. Aprile et al., Phys. Rev. Lett. 118 (2017) 101101
  • Search for two-neutrino double electron capture of 124Xe with XENON100, E. Aprile et al., Phys. Rev. C 95 (2017) 024605
  • XENON100 dark matter results from a combination of 477 live days, E. Aprile et al., Phys. Rev. D 94 (2016) 122001
  • The XENON dark matter search experiment, J. Naganoma et al., JINST 11 (2016) C02048
  • Low-mass dark matter search using ionization signals in XENON100, E. Aprile et al., Phys. Rev. D 94 (2016) 092001
  • Physics reach of the XENON1T dark matter experiment, E. Aprile et al., JCAP 04 (2016 )027
  • Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment, Eur .Phys .J. C 75 (2015) 546
  • Search for Event Rate Modulation in XENON100 Electronic Recoil Data, Phys. Rev. Lett. 115 (2015) 091302
  • Exclusion of Leptophilic Dark Matter Models using XENON100 Electronic Recoil Data, Science 349 (2015) 851
  • Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experiment, J. Inst. 9 (2014) P11006
  • First axion results from the XENON100 experiment, Phys. Rev. D 90 (2014) 062009
  • Observation and applications of single-electron charge signals in the XENON100 experiment, J. Phys. G: Nucl. Part. Phys. 41 (2014) 035201
  • Analysis of the XENON100 dark matter search data, Astropart. Phys. 54 (2014) 11-24
  • The neutron background of the XENON100 dark matter search experiment, J. Phys. G: Nucl. Part. Phys. 40 (2013) 115201
  • Response of the XENON100 dark matter detector to nuclear recoils, Phys. Rev. D, 88 (2013) 012006
  • Limits on spin-dependent WIMP-nucleon cross sections from 225 live days of XENON100 data, Physical Review Letters, 111 (2013) 021301
  • Longitudinal and transverse diffusion of electrons in high-pressure xenon, J. Inst. 8 (2013) C01028
  • The distributed Slow Control System of the XENON100 Experiment, J. Inst. 7 (2012) T12001
  • Electron Mobility and Longitudinal Diffusion Coefficient in High-Density Gaseous Xenon, Jpn. J. Appl. Phys. 51 (2012) 116301
  • Scintillation and ionization yields produced by alpha-particles in high-density gaseous xenon, Nucl. Instr. Meth. A, 683 (2012) 40-45
  • Density Dependence of the Longitudinal Diffusion Coefficient of Electrons in Xenon Jpn. J. Appl. Phys. 51 (2012) 048001
  • Dark Matter Results from 225 Live Days of XENON100 Data, Physical Review Letters, 109 (2012) 181301
  • The XENON100 dark matter experiment, Astropart.Phys. 35 (2012) 573-590
  • CsI-THGEM gaseous photomultipliers for RICH and noble-liquid detectors, Nucl. Instr. Meth. A, 639 (2011) 117–120
  • Dark Matter Results from 100 Live Days of XENON100 Data, Physical Review Letters, 107 (2011) 131302
  • Likelihood approach to the first dark matter results from XENON100, Phys. Rev. D, 84 (2011) 052003
  • A search for light dark matter in XENON10 data, Physical Review Letters, 107 (2011) 051301
  • Material screening and selection for XENON100, Astropart.Phys. 35 (2011) 43-49
  • Implications on inelastic dark matter from 100 live days of XENON100 data, Phys. Rev. D 84 (2011) 061101
  • Study of the electromagnetic background in the XENON100 experiment, Phys. Rev. D 83 (2011) 082001
  • Design and Performance of the XENON10 Dark Matter Experiment, Astroparticle Physics 34 (2011) 679-698
  • A Monte Carlo study of photoelectron transmission in Xe-CH4 and Ne-CH4 mixtures for CsI photocathodes, J. Phys. D: Appl. Phys. 43(2010) 065002
  • First Dark Matter Results from the XENON100 Experiment, Physical Review Letters 105 (2010) 131302
  • Measurements of photoelectron extraction efficiency from CsI into mixtures of Ne with CH4, CF4, CO2 and N2, J. Inst. 4 (2009) P11025
  • Photoelectron transmission efficiency in Ar-CH4 and Xe-CH4 mixtures: Experimental results. Nucl. Instr. Meth. A, 607 (2009) 587-590
  • The scintillation and ionization yield of liquid Xe for nuclear recoils, Nucl. Instr. Meth. A, 601 (2009) 339-346
  • Constraints on inelastic dark matter from XENON10, Phys. Rev. D, 80 (2009) 115005
  • Limits on spin-dependent WIMP-nucleon cross-section from the XENON10 experiment, Physical Review Letters 101 (2008) 91301
  • First Results from the XENON10 Dark Matter Experiment at the Gran Sasso Laboratory, Physical Review Letters 100 (2008) 21303
  • Xenon GPSC high-pressure operation with large-area avalanche photodiode, Nucl.Instr.Meth. A 575 (2007) 444-448
  • Secondary Scintillation Yield in Pure Xenon, J. Inst. 2 (2007) P05001
  • Performance of an LAAPD in a liquid xenon ionization and scintillation chamber, Nucl.Instr.Meth. A 551(2005) 356

Address/Location

Physics Department of the University of Coimbra
3004-516 Coimbra
Portugal
Phone Number: (+351) 239410667


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PhD/Jobs

There are currently both Ph.D. and Postdoc positions available.

For information and application please contact Prof. Jose Matias-Lopes (fcjam (at) gian.fis.uc.pt).

Outreach

2007:

The 6 most important Experiments in the World
2007-11-14, Discover Magazine
Link

Researchers use high-tech machines to detect mysterious dark matter
2007-08-12, Associated Press article, published in USA Today and Washington Post (AP)
Link

Liquid Xenon Detector Joins the Run for Dark Matter
2007-08-01, Physics Today, pp.16-18

Dark matter looks to be particularly wimpy
2007-04-17, Nature
Link

2010:

Portugueses em Destaque
Correio da Manhã, 29/09/2010, pág. 20, “Portugueses em destaque”

Investigadores da UC em busca da matéria negra do universo
Diário de Coimbra, 29/09/2010, pág. 3

Experiência XENON100: Próximo da Matéria Negra
Link

Physics World reveals its top 10 breakthroughs for 2010
2010-12-20, New Scientist
Link

Dark matter stays dark
2010-05-14, Nature
Link

Early Results from Large Dark Matter Detector Cast Doubt on Earlier Claims
2010-05-05, Scientific American
Link

Dark Matter Claims Thrown Into Doubt by New Data
2010-05-03, New Scientist
Link

Particle Detector Shows Promise, if Nothing Else
2010-05-03, The New York Times
Link

2011:

Eureka - A um passo da matéria negra
Link

Caça à matéria negra
Visão, 21-04-2011, 94

Cientistas de Coimbra estão na corrida pelo Nobel da Física
Link

Investigadores da FCTUC a um passo da matéria negra
Diário As Beiras, 19-04-2011, 11

José Matias – Identificação da matéria negra
Correio da Manhã, 19-04-2011, 20

Cientistas mais perto da matéria negra
Diário de Coimbra, 19-04-2011, 10

Matéria negra: detecção mais perto que nunca
Jornal i, 19-04-2011, 38

Portugueses querem ver matéria negra do universo
Diário de Noticias, 19-04-2011, 32

A um passo da matéria negra
Diário Económico, 19-04-2011, 7

A "um passo" da descoberta da matéria negra: experiência XENON100 apresenta os melhores resultados de sempre
Link

Programa Portugal em Directo
Programa Portugal em Directo, Antena 1, 18-04-2011

Ciência: Cientistas da Universidade de Coimbra integram equipa internacional que “persegue” descoberta da matéria negra
Link

A «um passo» da descoberta da matéria negra: experiência XENON100 apresenta os melhores resultados de sempre
Link

Coimbra na rota do Nobel
2011-03-17 Coimbra na rota do Nobel, Cnoticias, (2011) 38

2012:

Universidade de Coimbra ajuda a pesquisar matéria negra
Diário de Coimbra, 05/08/2012, pág. 5

XENON com resultado histórico na pesquisa da matéria negra
Diário das Beiras, 03/08/2012, pág. 24

Investigadores mais perto de descobrir a matéria negra
Diário das Beiras, 01/08/2012, pág. 6

2013:

Enlightening the dark (Sep 27, 2013)
Link

2015:

Investigadores de Coimbra participam em descoberta sobre matéria escura (21-08-2015)
Link

Portugal: Experiência XENON destaca-se na procura da matéria escura (22-08-2015)
Link

Investigadores da Universidade de Coimbra publicam na revista Science (24-08-2015)
Link

2 Steps Closer to the Search for Dark Matter and Dark Energy (21-08-2015)
Link

Projeto criado num dos maiores laboratórios subterrâneos procura matéria escura (11-11-2015)
Link

Matéria escura pode ser descoberta nos próximos dois anos (11-11-2015)
Link

Equipamento inédito para detetar matéria negra é inaugurado hoje em Itália (11-11-2015)
Link

Equipamento inédito para detetar matéria negra é inaugurado hoje em Itália (11-11-2015)
Link

Equipamento inédito para detetar matéria negra é inaugurado hoje em Itália (11-11-2015)
Link

Equipamento inédito para detetar matéria negra é inaugurado hoje em Itália (11-11-2015)
Link

Equipa internacional inaugura o XENON1T e dá um passo de gigante na procura de matéria escura (11-11-2015)
Link

Equipamento inédito para detetar matéria escura é inaugurado hoje em Itália (11-11-2015)
Link

Equipamento inédito para detetar matéria escura é inaugurado hoje em Itália (11-11-2015)
Link

MATÉRIA ESCURA PODE SER DESCOBERTA NOS PRÓXIMOS DOIS ANOS (11-11-2015)
Link

Equipamento inédito para detectar matéria escura é inaugurado hoje em Itália (11-11-2015)
Link

Um passo de gigante na procura de matéria escura (12-11-2015)
Link

2016:

Entrevista ao programa “Mentes que brilham”, Porto Canal (2016)
Link

2018:

Consórcio internacional com equipa de Coimbra lidera na procura pela matéria escura
Link

Cientistas da Experiência Internacional XENON discutem em Coimbra novos dados sobre a misteriosa matéria escura do Universo
Link

Novos dados sobre a misteriosa matéria escura do Universo
Link

Consórcio internacional com equipa de Coimbra lidera na procura pela matéria escura
Link

Matéria escura do Universo reúne cientistas mundiais em Coimbra
Link

Cientistas discutem em Coimbra novos dados sobre a misteriosa matéria escura do Universo
Link

2019:

Entrevista ao Café Central
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Cientistas encontram isótopo radioativo muito mais antigo do que o próprio Universo
Link

Um isótopo do xénon tem a meia-vida mais longa do Universol
Link

Cientistas encontram-se radioativos muito mais antigos que proprio Universo
Link

Um isótopo tem a meia-vida mais longa do Universo
Link

Cientistas encontram isótopo radioativo muito mais antigo do que o próprio Universo
Link

Um isótopo radioativo um bilião de vezes mais velho que o Universo
Link

Investigadores da Universidade de Coimbra ajudam a medir o mais longo tempo de vida média de sempre de um isótopo radioativo
Link

Portugal discovers a Radioactive Isotope 1 billion times older than the Universe
Link

A radioactive isotope one billion times older than the Universe!
Link

A radioactive isotope one billion times older than the Universe!
Link

A radioactive isotope one billion times older than the Universe!
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Universidade de Coimbra | Um isótopo radioativo um bilião de vezes mais velho que o Universo!
Link

Um isótopo radioativo um bilião de vezes mais velho que o Universo – Nature
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Cientistas de Coimbra ajudam a medir isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Medido isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Física | Projeto Xenon mede vida de isótopo radioativo um bilião de vezes mais velho que o Universo
Link

Medido isótopo radioactivo um bilião de vezes mais velho que o Universo, Diario de Coimbra, 25.04.2019"

Um isótopo radioativo um bilião de vezes mais velho que o Universo!
Link

Medido isótopo radioactivo um bilião de vezes mais velho do que o Universo
Link

Um isótopo radioativo um bilião de vezes mais velho que o Universo!
Link

Cientistas medem isótopo radioativo um bilião de vezes mais velho do que o Universo
Link

Um isótopo radioativo um bilião de vezes mais velho que o Universo!
Link

https://elvasnews.pt/a-meia-vida-mais-longa-do-universo/
Link

A meia-vida mais longa do Universo
Link

Entrevista ao programa “Os Dias do Futuro”
Antena 1, a partir do minuto 21:32
Link

Entrevista ao programa 90 segundos de ciência
Antena 1
Link

2020:

Eventos surpreendentes" aproximam cientistas da descoberta da matéria escura
Observador
Link

“Eventos surpreendentes” aproximam cientistas da descoberta da matéria escura
tvi24
Link

"Eventos surpreendentes" aproximam descoberta da matéria escura
theworldnews
Link

Cientistas pensam estar mais perto da detecção da matéria escura
Ardina News
Link

Cientistas mais perto da descoberta da matéria escura devido a «eventos surpreendentes»
Executive Digest
Link

Universidade de Coimbra | Descoberta de novas partículas?
Litoral Centro
Link

Cientistas portugueses desvendam segredos da matéria escura
Bom Dia Europa
Link

"Eventos surpreendentes" aproximam descoberta da matéria escura
Noticias ao Minuto
Link

Descoberta de novas partículas?
Beira News
Link

"Eventos surpreendentes" aproximam cientistas da descoberta da matéria escura
RTP
Link

Equipa com investigadores da UC pode ter descoberto novas partículas
Campeao das Provincias
Link

Existe mesmo matéria escura? "Eventos surpreendentes" aproximam cientistas da descoberta
Diário de Notícias
Link

Descoberta de novas partículas?
Elvasnews
Link

Discovery of new particles
Portugalinews
Link

Portugal: 'Surprising events' underway in detection of dark matter - researchers
Lusa
Link

"Eventos surpreendentes" aproximam cientistas da descoberta da matéria escura
Destak
Link

Descoberta de novas partículas?
Jornal do Luxemburgo
Link

Cientistas pensam estar mais perto da detecção da matéria escura
Publico
Link

Matéria escura: colaboração internacional XENON1T anuncia novas descobertas
Press Point
Link

"Eventos surpreendentes" aproximam cientistas da descoberta da matéria escura
Porto Canal.
Link

Investigadores da Universidade de Coimbra ajudam a descobrir novas partículas
Noticias de Coimbra.
Link

"Eventos surpreendentes" aproximam cientistas da descoberta da matéria escura
Sic Noticias.
Link

Consócio internacional pode ter descoberto novas partículas
e-global
Link

Descoberta de novas partículas?
Rua Direita
Link

“Eventos surpreendentes” aproximam cientistas da descoberta da matéria escura
Zap aeiou.
Link

Experimento de detecção de matéria escura captura “sinais inexplicáveis”
Zedd Brasil
Link

Experimento com a detecção de matéria escura registra “sinais inexplicáveis”
Turnozero
Link

Experimento de detecção da matéria escura capta "sinais inexplicáveis"
Tilt
Link

Experimento de detecção da matéria escura capta "sinais inexplicáveis"
bol
Link

Descoberta de novas partículas?
Pravda
Link