The LUX-ZEPLIN (LZ) Dark Matter Search

Lead Research Organisation: University of Sheffield
Department Name: Physics and Astronomy

Abstract

Direct dark matter experiments search for the extremely rare and very faint collisions expected to occur between the cold dark matter particles that are believed to permeate our galaxy and the nuclei of atoms in the active medium of a radiation detector. Weakly Interactive Massive Particles, or WIMPs, are hypothetical elementary particles weighing as little as a few protons or as much as several heavy nuclei; besides gravity, they would interact by the weak nuclear force, thereby providing a mechanics for their possible detection. The motivation to search for WIMP dark matter is strong, with theories that attempt to explain what lies beyond the Standard Model of Particle Physics providing very good candidates.

The LUX-ZEPLIN (LZ) experiment will deploy a 7-tonne liquid xenon WIMP detector at the 4850-foot level of the Sanford Underground Research Facility (SURF) after a 3-year construction phase. In this most quiet of environments, shielded from cosmic rays and local backgrounds, LZ will then operate for at least 3 years to hopefully find a handful of tell-tale signs of WIMP interactions. LZ will be so sensitive that it will be limited only by backgrounds from astrophysical neutrinos, which provide a fundamental limit to these searches. However, before neutrinos set in, this experiment has the potential to finally shed light on the nature of dark matter.

Planned Impact

This project will address the fundamental nature of the dark matter in the universe, of great importance to particle physics, astrophysics and cosmology. Our science output will directly impact these fields by constraining models of physics beyond the Standard Model, structure formation and evolution in the universe. The technologies and software we are developing will impact other areas of physics within the STFC remit, notably long-baseline neutrino oscillation experiments and neutrinoless double beta decay (0vBB) searches. Construction and operation of a multi-tonne noble gas time projection chamber impacts the UK and international neutrino physics communities seeking to develop detectors based on similar principles and technology. Challenges such as high voltage delivery, light collection, sensor readout, purification and electron transport, long-term stability data collection and analysis are all similar for proposed experiments such as LBNF, which is also expected to be located at SURF, and with significant UK involvement. Similarly, LZ will develop and employ leading ultra-low background techniques to construct an instrument capable of detecting the rarest particle interactions. Experiments searching for rare 0vBB decay have similar requirements on stringent radio-purity. The UK 0vBB community and their international partners will benefit from our material screening instrument development and radiation detection techniques.
Our outputs developing low-background material screening technology will find further application in a diverse range of applications outside physics. Mass-spectrometry instrumentation capable of detecting trace contaminants at parts-per-trillion levels in small samples provides unprecedented sensitivity for food safety, pharmaceutical, environmental, forensic and clinical research. Demonstration of successful screening for toxicity in spiked samples, beginning with titanium dioxide nanoparticles, has the potential for improving safety standards and impacting UK health. We will also investigate feasibility of measuring impact of uranium and thorium in silicon electronics chips from 2017. The alpha decays from U and Th progeny cause faults in integrated circuits; a problem that is increasingly significant as chips become smaller, and an area of active research. Coupled to our underground ultra-low background gamma spectroscopy capability, we can uniquely provide measures of the full U and Th chains, at sub-mBq/kg sensitivity, accounting for the complete alpha particle emission rates. Pre-screening Si and other construction materials with both mass spectrometry and gamma spectroscopy will allow manufacturers to increase reliability of their components and foster greater economic competitiveness of UK industry.
Our simulation work with muons and radioactivity will impact a multidisciplinary research on muon tomography applicable to carbon storage monitoring, monitoring radioactive waste, studying geological repositories, detection of illicit nuclear materials and similar projects involving muon or other particle detection.
Our research provides training for students and staff in a wide range of specialist skills that are readily transferrable to commercial, financial and industrial sectors. Radiation detection techniques are applicable to medical imaging and defence, particularly screening for special nuclear material. Data processing, analysis, statistical methods, programming, and Monte Carlo simulations are regularly employed in the banking and investment sectors. Construction of vacuum systems, gas recirculation and purification plants, photosensors and many other systems in LZ provide valuable engineering skills.
Finally, given the readily accessible nature of the topic of dark matter and deep underground operation, our research has always captured the public's imagination, providing significant outreach and engagement opportunity for dissemination of knowledge.

Publications

10 25 50
 
Description Consolidated Grant
Amount £100,000 (GBP)
Funding ID ST/N000277/1, only the fraction of the grant relevant to the LZ commissioning and exploitation is indicated in the cost 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Academic/University
Country United Kingdom
Start 04/2018 
End 09/2019
 
Description Particle Physics Consolidated Grant from the University of Sheffield - ATLAS, ATLAS upgrade, T2K, LBNE/F, Hyper-K, MICE, LZ, DMGS, DRIFT, R&D, KE
Amount £2,709,792 (GBP)
Funding ID ST/N000277/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Academic/University
Country United Kingdom
Start 10/2015 
End 09/2019
 
Description The LUX-ZEPLIN (LZ) Dark Matter Search
Amount £4,600,000 (GBP)
Funding ID ST/M003469/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Academic/University
Country United Kingdom
Start 04/2015 
End 03/2018
 
Description LZ 
Organisation Imperial College London
Country United Kingdom 
Sector Academic/University 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Description LZ 
Organisation Rutherford Appleton Laboratory
Department Particle Physics Department
Country United Kingdom 
Sector Public 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Description LZ 
Organisation University College London
Department Department of Physics & Astronomy
Country United Kingdom 
Sector Academic/University 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Description LZ 
Organisation University of Edinburgh
Department School of Physics and Astronomy
Country United Kingdom 
Sector Academic/University 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Description LZ 
Organisation University of Liverpool
Department Department of Physics
Country United Kingdom 
Sector Academic/University 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Description LZ 
Organisation University of Oxford
Department Department of Physics
Country United Kingdom 
Sector Academic/University 
PI Contribution Working together on the design and future construction of the LZ detector
Collaborator Contribution Working together on the design and future construction of the LZ detector
Impact LZ Conceptual Design Report, LZ Technical Design Report, LZ detector
Start Year 2013
 
Title Modified SOURCES4 code 
Description The original code SOURCES4 developed at LANL (USA) has been modified to allow more accurate calculation of neutron yield in (alpha, n) reactions on a large number of isotopes relevant to material construction for rare event experiments. 
Type Of Technology Software 
Year Produced 2014 
Impact The code is now widely used by physicists working with underground experiments for rare event searches. 
 
Title Muon simulation code 
Description A Monte Carlo code for modelling cosmic-ray muons at different underground sites (SURF at South Dakota, USA and Modane, France) 
Type Of Technology Software 
Year Produced 2013 
Open Source License? Yes  
Impact The code allows calculation of the muon fluxes and energy spectra underground. Initial simulations have been done for underground laboratories in Italy, France and others. In 2015 the model and method have applied to the SURF underground laboratory in the USA. 
 
Description Interview with the Register 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with the journalist from The Register on the LZ programme. An article published online.
Year(s) Of Engagement Activity 2016
URL https://www.theregister.co.uk/2016/08/01/upgraded_lux_experiment_hunt_for_dark_matter/
 
Description Physics World online 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with a journalist from Physics World Online, an article in this online journal.
Year(s) Of Engagement Activity 2015
URL http://physicsworld.com/cws/article/news/2015/apr/09/dark-matter-and-muons-are-ruled-out-as-dama-sig...
 
Description Public talks at the amateur astronomy society meetings 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Around 100 people attended several tialks in total

Several other invitations received
Year(s) Of Engagement Activity 2011,2012,2013