@ grandilab.uchicago

Searching for Dark Matter with Noble Liquid Technologies

"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery."
Enrico Fermi

What do we do?

To make it simple… we search for dark matter!

Does dark matter exist?

Well, the story is complicated. Observations of the cosmic microwave background fluctuation, large-scale galaxy surveys and studies of large-scale structure formation indicate that a huge fraction of the matter in the Universe is not visible. An exotic and not yet discovered species of elementary particle would explain all these observations. Several experiments have been built in last two decades to prove the existence of these elusive particles but their detection is challenging and we do not have yet a clear picture of what they are and if they really exist.

So, are you looking for something that might not exist?

You are right! That's what makes this field so fascinating, it is fundamental physics. Dark matter puzzle is a cutting edge science topic: 95% of the matter is dark and it is waiting for physicists to shed some light over it. Of course all this is risky but "nothing ventured, nothing gained!".

How do you search for it?

We build specialized, low-background detectors designed to identify rare and low-energy interactions, possibly induced by dark matter interacting with ordinary matter. We have been doing this by contributing to two major experimental efforts in the field: XENON1T (2015-now) and DarkSide-50 (2008-2015), respectively featuring ultrapure xenon and argon as targets for dark matter detection. Both detectors employ the so-called two-phase (gas/liquid) Time Projection Chamber (TPC) technology that allows to simultaneously detect ionization and excitation produced by even tiny energy depositions in the sensitive liquid volume. We are now building XENONnT, an even larger detector featuring with respect to XENOn1T a 4 times larger fiducial mass and a 1/10th background.

Is it easy?

Absolutely not! It is really challenging since the dark matter signal is expected to be really wimpy and the experimental technologies should be pushed to their edges to reach the needed sensitivities. That's why, together with the main experiments, we are running a set of smaller scale detectors that we use to study in great detail the noble liquid properties and the detection technology we are developing. These studies will play a crucial role for the interpretation of data acquired from the actual dark matter detectors.


The XENON1T two-phase xenon Time Projection Chamber (TPC) was operating at Laboratori Nazionali del Gran Sasso (LNGS) from 2016 till end of 2018 and opened the era of multi-ton noble liquid detectors for Dark Matter seraches. Thanks to its design, large fiducial mass (1 tonne fiducial), and ultra-low background, XENON1T set world-leading results on a variety of dark matter models and rare searches.

The UChicago group activities within the XENON1T program spanned from the preparation and assembly of the two-phase Time Projection Chamber, its commissioning and the development of the computing cyber-infrastructure for data-processing/analysis - hosted by the UChicago Research Computing Center. The group is strongly geared towards data analyses and Monte Carlo simulations, with group members serving as Analysis and Monte Carlo Coordinators and deeply involved in several major analyses.

With the XENON program moving to its next phase, XENONnT, the UChicago group took the lead in the design and construction of XENONnT TPC and led the installation at LNGS in early 2020. Now rthe group is contributing to early operations and commissioning. In parallel to this activity, the group upgraded the cyber-infrastructure to accommodate XENONnT needs and continue to contribute to the data analysis.

"Observation of Excess Electronic Recoil Events in XENON1T", E. Aprile et al. (XENON Collaboration), arXiv:2006.09721, Submitted to Phys. Rev. D (2020)

"A Search for Light Dark Matter Interactions Enhanced by the Migdal effect or Bremsstrahlung in XENON1T", E. Aprile et al. (XENON Collaboration), arXiv:1907.12771, Phys. Rev. Lett. (2019)

"Light Dark Matter Search with Ionization Signals in XENON1T", E. Aprile et al. (XENON Collaboration), arXiv:1907.11485, Submitted for publication to Phys. Rev. Lett. (2019)

"XENON1T Dark Matter Data Analysis: Signal Reconstruction, Calibration and Event Selection", E. Aprile et al. (XENON Collaboration), arXiv:1906.04717, Accepetd for publication on Phys. Rev. D (2019)

"XENON1T Dark Matter Data Analysis: Signal & Background Models, and Statistical Inference", E. Aprile et al. (XENON Collaboration), arXiv:1902.11297, Phys. Rev. D 99, 112009 (2019)

"The XENON1T data acquisition system", E. Aprile et al. (XENON Collaboration), arXiv:1906.00819, JINST 14, no.07, P07016 (2019)

"First detection of two neutrino double electron capture in 124Xe - the longest half-life ever observed directly", E. Aprile et al. (XENON Collaboration), arXiv:1902.11002, Nature 568, 532–535 (2019)

"Constraining the spin-dependent WIMP-nucleon cross sections with XENON1T", E. Aprile et al. (XENON Collaboration), arXiv:1902.03234, Phys. Rev. Lett. 122, 141301 (2019)

"First results on the scalar WIMP-pion coupling, using the XENON1T experiment", E. Aprile et al. (XENON Collaboration), arXiv:1811.12482, Phys. Rev. Lett. 122, 071301 (2019)

"Dark Matter Search Results from a One Ton-Year Exposure of XENON1T", E. Aprile et al. (XENON Collaboration), Phys. Rev. Lett. 121, 111302.

"First Dark Matter Search Results from the XENON1T Experiment", E. Aprile et al. (XENON Collaboration), Phys. Rev. Lett. 119, 181301.

"The XENON1T Dark Matter Experiment", E.Aprile et al. (XENON Collaboration), Eur. Phys. J. C (2017) 77: 881.

"Material radioassay and selection for the XENON1T dark matter experiment", E.Aprile et al., submitted to Eur. Phys. J. C (2017)

"Removing krypton from xenon by cryogenic distillation to the ppq level", E.Aprile et al., Eur. Phys. J. C (2017) 77: 275.

"Online 222Rn removal by cryogenic distillation in the XENON100 experiment", E.Aprile et al., Eur.Phys.J. C77 (2017) 77: 358.

"Results from a Calibration of XENON100 Using a Source of Dissolved Radon-220", E.Aprile et al., Phys. Rev. D 95, 072008 (2017)

UChicago Noble Liquids R&D

Our research, focused on the development and operation of the dark matter detectors, is complemented by R&D activities and auxiliary measurements, designed to test new ideas for next generation detectors as well as inform analyses of presently running dark matter searches. This is accomplished by means of small experimental setups operated in our lab or on neutron beam facilities like ISNAP at Notre Dame University and TUNL at Duke University.

"Model Independent Approach to the Single Photoelectron Calibration of Photomultiplier Tubes", R.Saldanha et al., Nucl.Instrum.Meth. A863 (2017) 35-46.
"Measurement of scintillation and ionization yield and scintillation pulse shape from nuclear recoils in liquid argon", H.Cao et al., Phys.Rev. D91 (2015) 092007
"Observation of the dependence on drift field of scintillation from nuclear recoils in liquid argon", T.Alexander et al., Phys.Rev. D88 (2013) 9, 092006

DARKSIDE-50 (our past...)

We contributed to the design, operation and data analysis of the DarkSide-50 detector since its inception. DarkSide-50 is a two-phase argon Time Projection Chamber (TPC). The detector, filled with special low-radioactivity argon extracted from ancient underground gas-reservoir, has operated at LNGS since October 2013, setting strong foundations for the potential exploitation of the technique in future, large multi-ton detectors.

Phys.Rev. D93 (2016) 081101
JINST 11 (2016) P03016
Phys.Lett. B743 (2015) 456-466
Astropart.Phys. 49 (2013) 44-51
JINST 5 (2010) P05003
Nucl.Instrum.Meth. A587 (2008) 46-51
Astropart.Phys. 28 (2008) 495-507
Nucl.Instrum.Meth. A574 (2007) 83-88

The Group

Luca Grandi, xenon1t / XENON1T PI

Prof. Luca Grandi

Associate Professor
@ UChicago Physics Department,
@ Enrico Fermi Institute,
@ Kavli Institute for Cosmological Physics

Jacques Pienaar, xenon1t / XENON1T member

Dr. Jacques Pienaar

Postodctoral Research Scholar @ KICP
(XENON1T, XENONnT, Noble Liquid R&D)

David Antón Martín, xenonnt / XENONnT member

David Anton Martin

UChicago Graduate Student
(XENONnT, Noble Liquid R&D)

Jianyu Long, xenonnt / XENONnT member

Jianyu Long

UChicago Graduate Student
(XENONnT, Noble Liquid R&D)

Lanqing Yuan, xenonnt / XENONnT member

Lanqing Yuan

UChicago Graduate Student
(XENONnT, Noble Liquid R&D)

Tori Ankel

Tori Ankel

UChicago Undergraduate
(Noble Liquid R&D, XENONnT)

Alumni and Former Group Members

Richard Saldanha, xenon1t / XENON1T PI

Dr. Richard Saldanha

now Scientist @ PNNL

Yann Guardincerri

Dr. Yann Guardincerri

Evan Shockley

Dr. Evan Shockley

now Postdoc @ UCSD

Nicholas Upole, xenon1t

Dr. Nicholas Upole

now Engineer @ Company

Thomas Wester

Thomas Wester

now Grad Student @ Boston University

Roger Roglans

Roger Roglans

now Grad Student @ UC Berkley

James Kingston, xenon1t

James Kingston

now Grad Student @ UCD

Tweets by XENON

News @ grandilab

Interested to join the group?

If you are a graduate or undergraduate student check with the PI if we have an open position.

+1 (773) 834-7659

Eckhardt Research Center
Office 485