| NSF Org: |
PHY Division Of Physics |
| Recipient: |
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| Initial Amendment Date: | August 22, 2018 |
| Latest Amendment Date: | July 28, 2020 |
| Award Number: | 1806395 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
William Wester
PHY Division Of Physics MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | September 1, 2018 |
| End Date: | August 31, 2021 (Estimated) |
| Total Intended Award Amount: | $480,000.00 |
| Total Awarded Amount to Date: | $480,000.00 |
| Funds Obligated to Date: |
FY 2019 = $160,000.00 FY 2020 = $160,000.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
450 JANE STANFORD WAY STANFORD CA US 94305-2004 (650)723-2300 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
476 Lomita Mall Stanford CA US 94305-4040 |
| 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): | Particle Astrophysics/Undergro |
| Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT 01002021DB 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 known particles. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. One of the most exciting quests in particle physics is the search for new particles beyond the Standard Model of particle physics. Extensions of the Standard Model predict not only new particles with large masses but also some with very small masses. Such a candidate is the axion, which has been introduced to explain the smallness of Charge-Parity (CP) violation in Quantum Chromodynamics and which turns out to also be a prime candidate for a constituent of the dark matter in the universe. The Axion Resonant InterAction DetectioN Experiment (ARIADNE) is designed to search for axion-mediated spin-dependent interactions between nuclei at sub-millimeter ranges. The experiment involves a rotating non-magnetic mass to source the axion field, and a dense ensemble of laser-polarized He-3 nuclei to detect the axion field by Nuclear Magnetic Resonance.
While participating in this research, a team of postdocs, graduate students, and undergraduate researchers will be broadly trained in the techniques of experimental atomic physics, optical pumping, nuclear magnetic resonance, low-temperature physics, micro-fabrication, magnetic shielding, vacuum systems, and modeling. This will be valuable preparation for work in basic or applied research, either in the U.S. or international work force or scientific community.
The signal from an axion field can be resonantly enhanced by properly modulating the axion potential at the nuclear spin precession frequency. The goal of this award is to complete construction of the experiment, bring it through its commissioning phase during which possible systematics will be evaluated, and start the early data taking stage, exploring new parameter space for the PQ axion. The method has the potential to improve previous experimental and astrophysical bounds on axions by several orders of magnitude and probe deep into the theoretically interesting regime for the PQ axion. The experiment is also sensitive to more exotic axion-like particles. The new method can ultimately exceed present laboratory constraints on spin-dependent short-range forces by up to 8 orders of magnitude and can improve on the combined laboratory/astrophysical limits by a factor of 10^4 in the axion mass range of ma between 10 micro-eV and 10 milli-eV, probing deep into the traditional "PQ-axion window".
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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.
Intellectual merit:
The QCD axion could simultaneously solve two of the biggest outstanding mysteries in particle physics (i.e. the Strong CP problem) and cosmology (i.e. Dark Matter). In addition, axions or axion-like particles occur quite generically in theories of physics beyond the standard model. If the QCD axion or an axion-like particle is discovered, it will revolutionize our view of the standard model of physics and cosmology. Even if the axion could be ruled out over some portion of its allowed mass window, it will be a very interesting result. While the focus in the particle astrophysics community has mainly been on cosmic axion searches, axions can also generate novel spin-dependent short-range forces between nuclei in table-top experiments.
The Axion Resonant InterAction Detection Experiment (ARIADNE) is a collaborative effort to search for the QCD axion using techniques based on nuclear magnetic resonance. Axions or axion-like particles will generically mediate short-range spin-dependent interactions between an ensemble of nuclear spins and an (un-polarized) attractor mass. In the experiment, a sample of laser-polarized 3He nuclear spins feels a fictitious “magnetic field” as the teeth of a sprocket-shaped tungsten attractor rotate past the sample at its nuclear Larmor precession frequency. Here the axion is acting as the mediating boson responsible for the interaction. The setup relies on a stable rotary mechanism and superconducting magnetic shielding, required to screen the 3He sample from ordinary magnetic noise.
The experiment sources the axion locally and can therefore constrain axions independently of the cosmic axion abundance. ARIADNE aims to probe QCD axion masses in the higher end of the traditionally allowed “axion window” of 1 μeV to 6 meV, complementary to dark matter haloscopes such as ADMX and its higher-frequency extensions. Unlike cavity-based searches, the experiment has no need to “scan” over the axion mass since it senses a wide range of masses simultaneously. The major goal of the project is to begin to explore the parameter region corresponding to the QCD axion, thereby extending the current experimental searches by several orders of magnitude. When combined with other existing and planned experimental efforts, ARIADNE will facilitate searching for the QCD axion over its entire allowed mass range.
The work performed in this round of funding was centered on testing several of the key components required for the experiment and designing the main experimental cryostat and dewar. The work on magnetic gradient cancellation strategies, 3He sample cell fabrication techniques, and rotary stage testing indicates promise for achieving design sensitivity or near-design sensitivity of the apparatus. Levels of residual magnetization in a prototype tungsten source mass were found to be at or near levels acceptable to reach ultimate design sensitivity in the experiment. Experimental tests of thin film superconducting shielding that are relevant for the ARIADNE setup were performed and shielding factors of order 10^8 have been achieved using a combination of thin film and foil shielding, yielding encouraging results for being able to attain design sensitivity in the final experiment.
The work we have performed in this funding cycle shows promise for eventually being able to operate the experiment at a level to make a meaningful contribution to the search for the QCD axion. Results attained thus far have been reported in 2 refereed journal articles,1 conference proceeding, and several invited and contributed talks have been presented at conferences, workshops, universities, and national labs.
Broader Impact:
Across the three U.S. institutions supported by the Collaborative Research proposal, three postdocs, four PhD students, two Masters students, and two undergraduate students took part in research that was partially supported by this award. The students working on this project as well as students within their groups, were exposed to valuable techniques which will help to make them attractive future members of the scientific workforce. Their training included optics, cryogenics, vacuum technology, lasers, computer-aided design and modeling, nanofabrication, electronics, data acquisition, and data analysis. The technology being developed in this project will have other impacts in the general area of precision magnetometry, including design of low magnetic field environment and novel detection schemes.
Last Modified: 01/20/2022
Modified by: Aharon Kapitulnik
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