| NSF Org: |
PHY Division Of Physics |
| Recipient: |
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| Initial Amendment Date: | August 21, 2017 |
| Latest Amendment Date: | May 5, 2023 |
| Award Number: | 1719270 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
William Wester
PHY Division Of Physics MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | September 1, 2017 |
| End Date: | April 30, 2024 (Estimated) |
| Total Intended Award Amount: | $636,448.00 |
| Total Awarded Amount to Date: | $715,733.00 |
| Funds Obligated to Date: |
FY 2018 = $184,130.00 FY 2019 = $159,094.00 FY 2020 = $134,094.00 FY 2021 = $54,285.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
6100 MAIN ST Houston TX US 77005-1827 (713)348-4820 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
6100 Main Street Houston TX US 77005-1827 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
OFFICE OF MULTIDISCIPLINARY AC, Particle Astrophysics/Undergro |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT 01001920DB NSF RESEARCH & RELATED ACTIVIT 01002021DB NSF RESEARCH & RELATED ACTIVIT 01002122DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
Multiple astronomical observations have established that about 85% of the matter in the universe is not made of normal atoms, but must be otherwise undetected elementary "dark matter" particles that do not emit or absorb light. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after the Big Bang. If WIMPs are the dark matter, then their presence in our galaxy may be detectable via scattering from atomic nuclei in detectors located deep underground to help reject backgrounds due to cosmic rays. Direct detection of WIMP dark matter would solve a fundamental mystery in particle physics and cosmology, providing a unique window to learning about the primary matter constituent of the Universe and of physics beyond the Standard Model of particle physics. This award supports the US groups involved in the XENON1T dark matter search program at the INFN Gran Sasso National Laboratory (LNGS) underground laboratory.
The XENON project continues to captivate the imagination of the public. This is evidenced, for example, by several TV shows such as "The Big Bang Theory", which on several occasions featured XENON plots and results. Public interest in science is encouraged through talks and outreach activities. XENON1T will play a significant role in solving the dark matter puzzle, by either detecting WIMPs, or putting them under immense pressure as viable dark matter candidates. In addressing this fundamental physics problem, these awards will engage many undergraduate and graduate students as well as post-doctoral researchers, exposing them to a variety of subjects in physics and cosmology, and training them in state-of-the-art technologies, thus preparing to become future leaders in the field. Finally, the instrumentation and techniques used in XENON are relevant to a wide range of applications, from areas in homeland security and medical imaging, to the analysis and statistical treatment of large data sets.
The program for the next four years will focus on the continued operation of the XENON1T experiment and its science data analysis. The international XENON Collaboration of 130 scientists continues to be led by the PI at Columbia University with key roles served by US members both in the management of the experiment and its scientific program. XENON1T uses the largest liquid xenon time projection chamber (TPC) built to-date, with 2 tonnes active Xe target, and the highest sensitivity to dark matter Weakly Interacting Massive Particles (WIMPs), at the level of 2 × 10^-47 cm^2 for 40 GeV WIMPs. With funding of this proposal, the US will remain in the lead of the direct search for dark matter well beyond the end of the decade.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
A significant number of independent astrophysical measurements clearly indicate the existence of an invisible dark (very rarely interacting) component of the Universe matter, apparently consisting of yet undetected new type of elementary particles.
The XENON direct dark matter search project aims to unravel the nature of dark matter by detecting its very rare interaction with xenon nuclei. This National Science Foundation grant enabled US XENON teams to conduct collaborative research at Columbia University in New York City, New York, Rice University, Houston, Texas, Purdue University, West Lafayette, Indiana, and the University of San Diego, San Diego, California, and the University of Chicago in Chicago, Illinois, together with our European colleagues to develop a next-generation ultra-sensitive detector called XENONnT.
The XENON Dark Matter Search experiment has developed a dual phase liquid/gas xenon time projection chamber (LXe TPC shown in the Picture 1), a position- and energy-sensitive detector that can distinguish between the nuclear recoils expected from Dark Matter interactions and the background interactions from energetic gamma-rays with the electrons of the atomic shell. This detector is cooled down to -140° F (-95° C), where inert xenon gas liquefies at a pressure of a car tires (~30 psi or 2 bar). This transparent liquid is not only a dense medium, about three times heavier than water, but also an excellent scintillator and a medium for ionization. The primary scintillation photons are detected immediately by arrays of photomultiplier tube, which are photodetectors that are sensitive to individual light photons. The electrons released in a Dark Matter interaction are drifted across up to ~5 ft (150 cm) before they are extracted into the gas phase by a strong electric field. Here they excite the atoms in the gas to scintillate abundantly, which allows measurement of the amount of charge and the location of the interaction.
The XENON Dark Matter experiment (shown in Picture 2) is located at the INFN Gran Sasso National Laboratory (LNGS). It is one of the largest underground laboratories, and a world-wide renowned research facility. LNGS is located between cities of L’Aquila and Teramo (about 95 miles (120 km) northeast of Rome) in central Italy, the underground structures are on the eastbound (toward Rome) side of the 6 miles (10 km) long highway tunnel that crosses the Gran Sasso mountains. The underground complex consists of three experimental halls named Hall A, Hall B and Hall C (each 110 yds (100 m) long, 22 yds (20 m) wide and 20 yds (18 m) high). XENON is located in the middle of Hall B shown in the Picture 3.
The 1,530-yards (1,400 m) rock above the laboratory's underground complex provides natural shield, reducing the flow of cosmic rays by a million times. In addition, the neutron flux is about a thousand times lower than at the surface, due to the very small amounts of uranium and thorium in the dolomitic limestone rocks of the Gran Sasso mountain. Both are critical for background reduction in our Dark Matter Search experiment.
Within the period of this grant, the XENONnT experiment has been constructed, and after commissioning it is now one of the leading experiments for Dark Matter direct search in the world today. We continue to improve our knowledge about new physics beyond the Standard Model of particle physics. Together with the experiments at the giant accelerator Large Hadron Collider and indirect searches for Dark Matter, XENONnT is a key player in the search for the Dark Matter Particles interactions.
During the IDM conference in LAquila (Italy) July 10,2024, the XENONnT Collaboration announced the first measurement of low-energy nuclear recoils from neutrinos produced in nuclear reactions inside the Sun. See Picture 4.
Last Modified: 07/18/2024
Modified by: Petr Chaguine
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