The Mu2e experiment will measure the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. The conversion process results in a monochromatic electron with an energy of 104.97 MeV, slightly below the muon rest mass. The goal of the experiment is to improve the previous measurement by four orders of magnitude and reach of a SES (single event sensitivity) of 3 x 10^{-17} on the conversion rate, a 90% CL of 8 x 10^{-17}, and a 5sigma discovery reach at 2 x 10^{-16}$. The experiment goal is obtained with a intense pulsed negative muon beam. The pulsed beam is essential to reducing backgrounds. The other essential element is a sophisticated magnetic system composed of three consecutive solenoids to form the muon beam. Mu2e will use an aluminum target and examine ~10^{18} stopped muons in three years of running. The Mu2e experiment is under design and construction at the Fermilab Muon Campus. The experiment will begin data-taking near the end of 2020 with 3 years of running from 2021 to 2023. Upgrades to other materials than aluminum are already planned. This article is written specifically for younger researchers to bridge the gap between conference presentations and detailed design reports, and examines issues not covered in the former without the details of the latter.

The Mu2e Experiment

We report on an effort to improve the performance of superconducting radiofrequency cavities by the use of heat treatment in a temperature range sufficient to dissociate the natural surface oxide. We find that the residual resistance is significantly decreased, and we find an unexpected reduction in the BCS resistance. Together these result in extremely high quality factor values at relatively large accelerating fields Eacc ~20 MV/m: Q0 of 3-4x10^11 at <1.5 K and Q0 ~5x10^10 at 2.0 K. In one cavity, measurements of surface resistance versus temperature showed an extremely small residual resistance of just 0.63+/-0.06 nOhms at 16 MV/m. SIMS measurements confirm that the oxide was significantly dissociated, but they also show the presence of nitrogen after heat treatment. We also present studies of surface oxidation via exposure to air and to water, as well as the effects of very light surface removal via HF rinse. The possibilities for applications and the planned future development are discussed.

Ultra-Low Surface Resistance via Vacuum Heat Treatment of Superconducting Radiofrequency Cavities

We report on an effort to improve the performance of superconducting radiofrequency cavities by using heat treatment in a temperature range sufficient to dissociate the natural surface oxide. We find that the residual resistance is decreased significantly, and we find an unexpected reduction in the Bardeen-Cooper-Schrieffer (BCS) resistance. Together these result in extremely high-quality factor values at relatively large accelerating fields ${E}_{\mathrm{acc}}$ \ensuremath{\sim} 20 MV/m: ${Q}_{0}$ = 3--4 \ifmmode\times\else\texttimes\fi{} ${10}^{11}$ at 1.5 K and ${Q}_{0}$ \ensuremath{\sim} 5 \ifmmode\times\else\texttimes\fi{} ${10}^{10}$ at 2.0 K. In one cavity, measurements of surface resistance versus temperature showed an extremely small residual resistance of just 0.63 \ifmmode\pm\else\textpm\fi{} 0.06 n\ensuremath{\Omega} at 16 MV/m. Secondary ion mass spectrometry measurements confirm that the oxide is dissociated significantly, but they also show the presence of nitrogen after heat treatment. We also present studies of surface oxidation via exposure to air and to water, as well as the effects of very light surface removal via HF rinse. The study is performed on 1.3 GHz cavities, but the effect may be extendable to other frequencies as well. The possibilities for applications and the planned future development are discussed.

Ultralow Surface Resistance via Vacuum Heat Treatment of Superconducting Radio-Frequency Cavities

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.

Scientific Opportunities with the Long-Baseline Neutrino Experiment

A total of ten jacketed single-spoke resonators type 1 (SSR1) have been fabricated for Fermilab’ injection experiment (PIP2IT). PIP2IT is a test bed for Fermilab’s future accelerator named proton improvement plan II that is currently under development. SSR1 cavities operate at 325 MHz to accelerate a proton beam at a relative (to speed of light) velocity ( $\beta = 0.22$ ). In this paper, we present Fermilab’s experience in developing those spoke resonators starting from the design and analysis phase, to fabrication and extensive testing to qualify cavities for cryomodule assembly.

Development of Low $\beta $ Single-Spoke Resonators for the Front End of the Proton Improvement Plan-II at Fermilab

The Proton Improvement Plan-II (PIP-II) encompasses a set of upgrades and improvements to the Fermilab accelerator complex aimed at supporting a world-leading neutrino program over the next several decades. PIP-II is an integral part of the strategic plan for U.S. High Energy Physics as described in the Particle Physics Project Prioritization Panel (P5) report of May 2014 [1] and formalized through the Mission Need Statement approved in November 2015. As an immediate goal, PIP-II is focused on upgrades to the Fermilab accelerator complex capable of providing proton beam power in excess of 1 MW on target at the initiation of the Long Baseline Neutrino Facility/Deep Underground Neutrino Experiment (LBNF/DUNE) program [2], currently anticipated for the mid- 2020s. PIP-II is a part of a longer-term goal of establishing a high-intensity proton facility that is unique within the world, ultimately leading to multi-MW capabilities at Fermilab....

/pdf/the-pip-ii-conceptual-design-report-1rokge6bm3.pdf

The PIP-II Conceptual Design Report

A new test stand dedicated to Superconducting Radiofrequency (SRF) cryomodule testing, CMTS1, has been commissioned and is now in operation at Fermilab. The first device to be cooled down and powered in this facility is the prototype 1.3 GHz cryomodule assembled at Fermilab for LCLS-II. We describe the demonstrated capabilities of CMTS1, report on steps taken during commissioning, provide an overview of first test results, and survey future plans.

Commissioning And First Results From The Fermilab Cryomodule Test Stand

http://inspirehep.net/record/1239519/files/arXiv:1306.5022.pdf

Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts

In recent years, we have packaged the Fermilab accelerator control system, Acnet, so that other instances of Acnet can be deployed, independent of the local Fermilab infrastructure. This encapsulated Acnet, also referred to as Acsys-in-a-Box, is installed as the detector control system at the NOQA Far Detector. NOQA is a neutrino experiment using a beam of particles produced by the Fermilab accelerator chain. To fulfill the experimental goals, there are two detectors: a 200 ton ``Near Detector'' on the Fermilab campus and a 14000 ton ``Far Detector'' 810 km away in northern Minnesota. All key tiers and aspects of Acnet are available in the NOQA instance, including the central device database, Java Open Access Clients, Erlang front-ends, application consoles, synoptic displays, and state notifications. Acnet at NOQA is used for power-supply control, monitoring detector position and strain gauges, environmental control, PLC supervision, relay rack monitoring, and interacting with the Epics PVs which instrument the detector's scientific data acquisition hardware. We discuss the challenges of maintaining a control system in a remote location, synchronizing updates between the instances, and improvements made to Acnet as a result of our NOQA experience.

J. Patrick

Papers

The PIP-II Conceptual Design Report

Commissioning And First Results From The Fermilab Cryomodule Test Stand

Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts

Detector Controls for the NOvA Experiment Using Acnet-in-a-Box