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 is the only ton-scale (generation two, G2) built in the world.

It is in the final commissioning phase and it is due to start taking data in April 2016 reaching the WIMP sensitivity limit (two orders of magnitude below the one set by XENON100) after 2 years of operation. Real-time news on the progress of XENON1T can be followed in xenon1t.org

Exclusion limit curves for the WIMP-nucleon spin-independent interaction
achieved by different experiments and projected for XENON1T in 2017 aswell as its upgrade XENONnT (7 ton Xe).


Latest results

August 2015

The most recent results on Science (Science 349 (2015) 851, http://arxiv.org/abs/1507.07747) and in Physical Review Letters (Phys. Rev. Lett. 115 (2015) 091302, http://arxiv.org/abs/1507.07748) are obtained from the analysis of XENON100 data on the search for WIMPs (Weakly Interactive Massive Particles), the preferred dark matter candidates.

The results clearly rule out the leptophilic dark matter hypothesis brought by DAMA/LIBRA as the single explanation for their controversial annual modulation signal, claimed as low mass dark matter. We exclude leptophilic models as an explanation for the 17 year old standing DAMA/LIBRA signal, such as couplings to electrons through axial-vector interactions at a 4.4 sigma confidence level, mirror dark matter at 3.6 sigma, and luminous dark matter at 4.6 sigma.

The XENON100 experiment is a powerful dark matter detector with a 62 kg target of hyper-pure liquid xenon, acquiring data at the underground laboratory of Gran Sasso, Italy, under 1300m of rock to drastically reduce the cosmic ray intensity hitting the detector, which would otherwise hide the rare dark matter events. The 20 times larger XENON1T detector (and its upgrade with 7 ton, XENONnT) allows anticipating for an exciting decade in the search for the answer to this fundamental cosmology mystery.


Team Members

Current Coimbra XENON team:

Former Coimbra XENON team:


Collaboration

Institutes involved in the XENON Project:












Publications

  • 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


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

XENON100 poderá ser a primeira experiência a detectar Matéria Negra do Universo
Link

Experiência XENON100 a mais bem posicionada para ser a primeira detectar 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

Matéria negra. Detecção mais perto do que nunca
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
Link

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

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

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

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

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

A um passo da matéria negra - experiência XENON revela medições sem precedentes
Link

Investigadores da Faculdade de Ciências e Tecnologia da Universidade de Coimbra na Experiêcia Xenon
Link

Portugueses avançam para descoberta de matéria negra
Link

Portugueses em busca da matéria negra
Link

Cientistas Universidade Coimbra «perseguem» matéria negra
Link

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


2012:

República do Saber (21 setembro 2012)
Link

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

Experiência XENON estabelece novos limites na detecção de matéria escura
Link


2013:

Enlightening the dark (Sep 27, 2013)
Link


2015:

Experiência XENON destaca-se na procura de matéria escura (21-08-2015)
Link

UC: Investigadores participam em experiência internacional sobre matéria escura (21-08-2015)
Link

Portugueses participam em experiência XENON(21-08-2015)
Link

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

UC participa em investigação para descoberta de matéria escura (22-08-2015)
Link

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

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

Em busca da matéria escura: UC é uma das nove instituições envolvidas (23-08-2015)
Link

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

Investigadores de Coimbra procuram matéria escura (25-08-2015)
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