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At least 127 records · Page 7

Simulation of Bunch Formation for the Mu2e Experiment

The Fermilab Recycler is an 8 GeV storage ring composed of permanent magnets that was crucial to the success of the Fermilab Tevatron Collider program. It is currently being used to slip-stack protons for the high energy neutrino program and to re-bunch protons for use in the Muon g-2 and Mu2e experiments. For the latter applications, the Recycler re-bunches each 1.6 µs "batch" from the Fermilab Booster into four 2.5 MHz bunches. For the Mu2e experiment, it is crucial that beam more than 125 ns from the nominal bunch center be suppressed by at least a factor of 1E-5. While bunch formation is currently in operation for the g-2 experiment, this out of time requirement has not been met, and the reason is not understood. This work presents a simulation of bunch formation in the Recycler, in an effort to understand the reason for this excessive out of time beam and to search for a way to reduce it.

43 PARTICLE ACCELERATORS↗

Synchronization and phase locking of resonant magnet power supplies for Mu2e experiment at Fermilab

The Mu2e Experiment has stringent beam structure requirements; namely, it requires short (~200 ns) proton bunches separated by 1.5-2.0 $\mu$s. This beam structure will be produced using the Fermilab 8 GeV Booster, the 8 GeV Recycler Ring, and the Delivery Ring, which was formerly part of the antiproton accumulator system. Out of time beam is limited to a fraction of level of no more than $1\times 10^{-10}$, a requirement known as "extinction". Achieving this level of extinction requires a system of resonant magnets and collimators, phased such that only in time particles will pass through. The Mu2e magnet system involves two components: a 300 kHz component, timed such that the 600 kHz beam will pass through the collimators at the nodes, and a 4.5 MHz system to reduce the slewing of the in-time beam. These two systems must be precisely phase locked to the bunch rate coming from the Delivery Ring, which itself must be phased to match beam transfers coming from the Recycler. This poster describes the control system for the magnets, which is based on an Intel Arria FPGA, which handles phase locking of the magnets to the Delivery Ring, including the phase jumps required to match transfers from the Recycler.

43 PARTICLE ACCELERATORS↗

A data-driven method to estimate the antiproton background in Mu2e

The Mu2e experiment will search for the CLFV process of neutrinoless, coherent conversion of muon to electron in the field of an Al nucleus. One of the expected backgrounds is antiprotons produced by the proton beam at the Production Target and annihilating in the Stopping Target to produce signal-like electrons. Although not a dominant background, it has a large uncertainty and cannot be suppressed by the timing cuts used to reduce the prompt background. However, at Mu2e energies, $p\bar{p}$ annihilation is the only source of events with multiple, simultaneous particles coming from the Stopping Target. We utilized this unique feature and developed a novel approach to reconstruct multi-track events and estimate the antiproton background.

Chithirasreemadam, Namitha [Pisa U.; INFN, Pisa]↗

Mu2e Technical Design Report

Fermi National Accelerator Laboratory and the Mu2e Collaboration, composed of about 155 scientists and engineers from 28 universities and laboratories around the world, have collaborated to create this technical design for a new facility to study charged lepton flavor violation using the existing Department of Energy investment in the Fermilab accelerator complex. Mu2e proposes to measure the ratio of the rate of the neutrinoless, coherent conversion of muons into electrons in the field of a nucleus, relative to the rate of ordinary muon capture on the nucleus. The conversion process is an example of charged lepton flavor violation (CLFV), a process that has never been observed experimentally. The significant motivation behind the search for muon-to-electron conversion is discussed in Chapter 3.

43 PARTICLE ACCELERATORS↗

Final Technical Report: Mu2e at the City University of New York

This DOE grant award for was for the period June 1, 2013 to March 31, 2016. Popp was awarded an internship in the Visiting Faculty Program at FNAL in summer of 2015; consequently the unused portion of summer salary funds allowed us to apply for a no-cost extension with our remaining funds until March 31, 2017. That support furnished us with the means to carry out numerous successful projects for Mu2e for nearly four years. Up to now, the driving force to our work has been dictated primarily by the Mu2e Project cost and schedule needs. Our work has been under the purview of three of the Working Groups to which we belong: Target Station, Electron Tracker, and Stopping Target Monitor. We have carried out a mix of bench-top testing tasks locally, more elaborate work at Fermilab every summer, and extensive software development and simulation studies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Thermal Analysis of Fermilab Mu2e Beamstop and Structural Analysis of Beamline Components

The Mu2e project at Fermilab National Accelerator Laboratory aims to observe the unique conversion of muons to electrons. The success or failure of the experiment to observe this conversion will further the understanding of the standard model of physics. Using the particle accelerator, protons will be accelerated and sent to the Mu2e experiment, which will separate the muons from the beam. The muons will then be observed to determine their momentum and the particle interactions occur. At the end of the Detector Solenoid, the internal components will need to absorb the remaining particles of the experiment using polymer absorbers. Because the internal structure of the beamline is in a vacuum, the heat transfer mechanisms that can disperse the energy generated by the particle absorption is limited to conduction and radiation. To determine the extent that the absorbers will heat up over one year of operation, a transient thermal finite element analysis has been performed on the Muon Beam Stop. The levels of energy absorption were adjusted to determine the thermal limit for the current design. Structural finite element analysis has also been performed to determine the safety factors of the Axial Coupler, which connect and move segments of the beamline. The safety factor of the trunnion of the Instrument Feed Through Bulk Head has also been determined for when it is supporting the Muon Beam Stop. The results of the analysis further refine the design of the beamline components prior to testing, fabrication, and installation.

Narug, Colin S.↗

Mu2e Calorimeter Clustering Studies [Slides]

aMu2e (muon-to-electron-conversion), an Intensity Frontier experiment at Fermilab set to begin data taking in 2022, will search for flavor violation in charged leptons with a muon decaying to only an electron without any neutrinos. Protons will be accelerated by the 8GeV proton beam before reaching Mu2e’s production target. From there, pions enter an S-shaped Transport Solenoid and travel through a series of absorbers and collimators to select low-energy negatively charged muons from pion decay that will hit the stopping target. Downstream from the stopping target are a curved straw tracker and two annular disk crystal calorimeters. The signal will be a mono-energetic e- with an energy close to the rest mass of a muon. The Mu2e expected single event sensitivity is 2.87e-17. The complimentary trigger strategy will take advantage of both online track searches from the tracker and calorimeter reconstruction. The trigger requires a rejection factor greater than 100 and m ust make its decision within a 3ms time budget. In order to provide high efficiency on signal events, our calorimeter clustering algorithms must be accurate and meet the timing performance. I will discuss the expected performance of two clustering algorithms: a fast algorithm to be used at the trigger level and a more accurate clustering algorithm to be used in the offline reconstruction. The fast algorithm defines clusters by only selecting crystals adjacent to a high energy crystal seed. The full-blown algorithm can find smaller clusters separated from the main cluster, within a distance and timing window, and combine them into one cluster. We have analyzed the topology of the reconstructed clusters by the two algorithms on events with only a conversion electron and combined signal and background events. The goal of these studies is to improve the performance of the fast algorithm to better reconstruct the cluster energy and work within the strict timing budget.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Target Studies for Mu2e-II

In Mu2e-II 800 MeV protons at 100 kW will be used, rather than the 8 GeV 8 kW planned for Mu2e. The higher power and lower beam energy will require some significant changes in the production target. Multiple scattering is much more significant, requiring changes in the target geometry and material. Active cooling is needed and the target geometry should be modified to match the beam trajectories. Low-Z targets may be preferable because of their reduced multiple scattering and target heating effects. Production of positive secondaries ($\pi^+, \mu^+$) appears to be enhanced, suggesting that the PIP-II program should be adapted to include ($\pi^+, \mu^+$) experiments.

43 PARTICLE ACCELERATORS↗

The Mu2e Crystal Calorimeter [PowerPoint]

The talk describes the Mu2e experiment, including an introduction on CLFV and the experimental layout, and then covers Mu2e electromagnetic calorimeter, including components, performance and a production status.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The Mu2e Tracker [PowerPoint]

The Mu2e experiment at Fermilab will improve the sensitivity by four orders of magnitude.The Mu2e tracker has been designed to: provide accurate reconstruction of e- momentum and operate in a very harsh environment (high γ and neutron dose). The first 3 panels built and already under test and good agreement of data with our Monte Carlo simulation has been found. The QA process and plane assembly have been started.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The Mu2e Experiment [PowerPoint]

The presentation includes: Motivation and Theory; Experiment Overview; Experiment Design (Proton Beam, Solenoids, Production and Stopping Targets, Tracker, Calorimeter, CRV, DAQ/Trigger); Mu2e Shcedule; Mu2e II; and, Summary.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Design of the Mu2e Straw Tracker

The design and challenges of the Mu2e straw tracker is given in context of the Mu2e apparatus.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The Mu2e Experiment [PowerPoint - May 2018]

The following topics are presented: Motivation and Theory; Experiment Overview; Experiment Design (including Proton Beam, Production and Stopping Targets, Teracer, Calorimeter, CRV, DAQ/Trigger); Mu2e Schedule; Mu2e II; and, Summary.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

The Mu2e Calorimeter Final Technical Design Report

Since the first version of the Mu2e TDR released at the beginning of 2015, the Mu2e Calorimeter system has undergone a long list of changes to arrive to its final design. These changes were primarily caused by two reasons: (i) the technology choice between the TDR proposed solution of BaF2 crystals readout with solar blind Avalanche Photodiodes (APDs) and the backup option of CsI crystals readout with Silicon Photomultipliers (SiPM) has been completed and (ii) the channels numbering, the mechanical system and the readout electronics were substantially modified while proceeding with engineering towards the final project. This document updates the description of the calorimeter system adding the most recent engineering drawings and tecnical progresses.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Data-driven Alignment of the Tracker for the Mu2e Experiment

An alignment of the Mu2e Tracker is investigated using the Mu2e Offline Software and Millepede-II. Simulated misalignments of Tracker planes were inserted between Monte-Carlo event generation and before reconstruction using randomly generated $(x,y,z)$-translations and rotations of the rigid-body planes in the detector model. Cosmic ray muons, with no magnetic field present in the Detector Solenoid, will follow a straight-line trajectory. A maximum-likelihood fit is used to reconstruct a track and determine its parameters. Tracks traversing at least four planes, with ten registered straw hits, and a maximum time residual of $20$ ns are selected to be used in an alignment sample. The cuts were chosen to discard tracks with low information content, such as those with high levels of multiple scattering or those with low numbers of measurements contributing to a single track fit. Millepede-II produces the resulting alignment constants according to a simultaneous least-squares fit of the alignment parameters and the track parameters for all input tracks. The improved alignment constants are used to repeat the process and recover an increased number of suitable tracks, further improving the estimate of the alignment constants in subsequent iterations. A performance study of the process was conducted on a misaligned Tracker in the case of translation-only, and translation plus rotational misalignments. In both cases, the correct alignment constants were recovered to within statistical error after three global fit iterations. Additionally, a continuous integration system was developed for the \texttt{Mu2e/Offline} GitHub repository, introducing a convenient automated testing process for all proposed changes (``pull requests"). The tests developed included a full build of the software, followed by tests of the validation routines, geometry overlap checking, and multi-threading mode. Additionally, code quality checks and low-statistics physics comparison checks a re also available.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Simulating target tests at AP0 facility for Mu2e

The predicted production of muons and energy deposition for the production target of the Mu2e experiment are dependent on the documentation of cross-sections values, the properties of the target’s material, etc. Hence, making real tests on similar targets before its use on Mu2e will be a good indicator of the accuracy of the simulations done for the experiment. The main goal of the project is to simulate a target test at the AP0 Target Facility, previously used to create the muon beam for the Muon g-2 experiment. Results from these simulations will be used as input to engineering models of the target to produce predicted stress and surface temperature distributions, parameters that will later be measured in future beam runs to validate underlying cross section models.

Delgado, Amii Matamoros↗