The R&D described in the award Superconducting RF (SRF) Development for the Project X Neutrino Beam to DUSEL is viewed as highly relevant, and can be is of national and international importance. The science that could be enabled by this R&D includes programs at DUSEL, the proposed Deep Underground Science and Engineering Laboratory in South Dakota.
Project X is a collection of experiments proposed to compose a future Fermilab program. A component of such a program is likely to consist of measurements of neutrino properties. Physicists now think that neutrinos could provide answers to some of the puzzling questions not addressed by the Standard Model. In particular, physicists think that neutrinos might be the reason that we exist: their interactions could explain why matter is abundant while antimatter disappeared in our universe. The proposed Long-Baseline Neutrino Experiment aims to find out whether that is the case. It will explore the interactions and transformations of the world's highest-intensity (made possible through SRF R&D) neutrino beam by sending it from Fermilab more than 1,000 kilometers straight through the earth to the largest particle detectors ever built. The detectors could be housed in the proposed DUSEL laboratory.
Superconducting radiofrequency is a key enabling technology for state-of-the-art particle accelerators. It is of critical importance to Fermilab 's Project-X, future Linear Colliders, and to future accelerators for high-energy and nuclear physics as well as next-generation light sources such as those based on energy-recovery linacs and free-electron lasers. SRF applications cover a very broad range of accelerator and beam parameters; cost savings in SRF can determine the feasibility of a particular design or whether a project is funded at all. Small improvements in achievable SRF cavity performance can lead to significant reductions in construction and operating costs of major accelerator-based facilities. The basic physics and chemistry governing SRF cavity limits and behavior at the niobium surface is still insufficiently understood, and it is still impossible to guarantee that a particular cavity fabricated and processed according to a particular recipe will actually meet its specifications. No US vendors can match European or Asian vendors in cavity quality, achievable gradient, or production reproducibility. US industry on its own cannot undertake the necessary R&D. Intellectual and practical mentorship of US industry by university and laboratory experts is a step on a path that American industry can follow to help it regain leadership in many specialized high-tech areas, including SRF.
The frontiers of science are often shaped by accelerator physics and technology. As examples, SRF has opened up a new world in nuclear physics and neutron production; the short x-ray pulses from free electron lasers will revolutionize atomic and molecular physics, and accelerator science will determine the future of its progenitor, particle physics, where inventions are needed to overcome size and cost limitations.
This collaboration is positioned to make substantial progress in understanding, improving, and detailing the important steps in fabricating and processing cavities. The US vendors who become partners in this program will benefit in that they can begin to learn how to successfully compete with the rest of the world on US and international cavity procurements. It is also worth noting that accelerator science is a very forward-looking area for a young scientist to pursue.
Project-X, recently renamed to PIP-II will likely be the largest elementary-particle physics experiment in the US. Among other insights, it will use neutrinos to analyze why the universe is made of matter rather than anti matter. The linear accelerator that ultimately produces the neutrinos will be built with the advanced technology of superconducting accelerating structures. This technology has been pioneered by Cornell University, and this grant allowed us to push it to new performances suitable for Project-X. Hitherto, superconducting accelerating structures have been optimized to provide the highest energy in the shortest distance, to reduce the length and therefore the cost of an accelerator. But the accelerator cost for Project-X is not dominated by its length, but by the cost for cooling the accelerator to about 2 Kelvin. Cornell therefore endeavored to find procedures that produce cavities with the smallest possible surface resistivity and reduced cooling needs. These procedures are important for an increasing number of particle accelerators including CEBAF, ATLAS, Project-X, SNS, the European XFEL, and LCLS-II. Some of these accelerators produce electrons, others protons or ions. But they have the following in common: to avoid overheating, these accelerators are based on superconducting accelerating structures. The most relevant technological findings were: (a) Optimization of a Vertical Electro-Polishing system, now adopted by two other international laboratories. (b) Surface treatment with HF to produce a pristine oxide layer in the inside of the accelerating structures. (c) Pioneered the reduction of surface heating by thermal cycling around the superconducting transition temperature. These findings have allowed us to produce a multi-cell accelerating cavity of about one yard length that has the world’s lowest surface losses. Students on both the graduate and undergraduate level have participated in this work, including summer students from other universities through the NSF-funded REU program and students from community colleges through our SRCCS program. An extensive outreach program with both national and regional elements for the general public and K-12 students has drawn on the personnel and activities of the proposed work. The laboratory’s intellectual and physical resources has been used to promote the adventure of science directly to young people as well as provide workshops and direct support for teachers of science in their own classrooms and in group-settings on campus. In addition we have been working with underrepresented populations in both urban settings of New York City and rural areas here on the edge of Appalachia. Creation of materials for the classroom is also an important part of our work in helping teachers in New York State deal with changing science curricula.
