Muon Collider Forum report

A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively clean leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&D. Findings of the Forum are summarized in this report

A Muon Collider Facility for Physics Discovery

Muon colliders provide a unique route to deliver high energy collisions thatenable discovery searches and precision measurements to extend ourunderstanding of the fundamental laws of physics. The muon collider design aimsto deliver physics reach at the highest energies with costs, power consumptionand on a time scale that may prove favorable relative to other proposedfacilities. In this context, a new international collaboration has formed tofurther extend the design concepts and performance studies of such a machine.This effort is focused on delivering the elements of a $\sim$10 TeV center ofmass (CM) energy design to explore the physics energy frontier. The path tosuch a machine may pass through lower energy options. Currently a 3 TeV CMstage is considered. Other energy stages could also be explored, e.g. ans-channel Higgs Factory operating at 125 GeV CM. We describe the status of theR&D and design effort towards such a machine and lay out a plan to bring theseconcepts to maturity as a tool for the high energy physics community.<br

The physics case of a 3 TeV muon collider stage

In the path towards a muon collider with center of mass energy of 10 TeV ormore, a stage at 3 TeV emerges as an appealing option. Reviewing the physicspotential of such muon collider is the main purpose of this document. In orderto outline the progression of the physics performances across the stages, a fewsensitivity projections for higher energy are also presented. There are manyopportunities for probing new physics at a 3 TeV muon collider. Some of themare in common with the extensively documented physics case of the CLIC 3 TeVenergy stage, and include measuring the Higgs trilinear coupling and testingthe possible composite nature of the Higgs boson and of the top quark at the 20TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stemfrom the fact that muons are collided rather than electrons. This isexemplified by studying the potential to explore the microscopic origin of thecurrent $g$-2 and $B$-physics anomalies, which are both related with muons.<br

Muon Collider Physics Summary

The perspective of designing muon colliders with high energy and luminosity,which is being investigated by the International Muon Collider Collaboration,has triggered a growing interest in their physics reach. We present a concisesummary of the muon colliders potential to explore new physics, leveraging onthe unique possibility of combining high available energy with very precisemeasurements.<br

Muon Collider Physics Summary

The perspective of designing muon colliders with high energy and luminosity,which is being investigated by the International Muon Collider Collaboration,has triggered a growing interest in their physics reach. We present a concisesummary of the muon colliders potential to explore new physics, leveraging onthe unique possibility of combining high available energy with very precisemeasurements.<br

Study on discharge and short circuit generation in CMS GE1/1 triple-GEM detectors during Run 3

The installation of the new GE1/1 station of Gas Electron Multiplier (GEM) detectors in the Compact Muon Solenoid (CMS) experiment was completed during the Long Shutdown 2 (LS2) phase of the Large Hadron Collider (LHC). The GE1/1 station has been operational in the CMS detector since the beginning of the Run-3 data-taking phase, and for the first time the GEM technology was deployed on a large scale, comprised of 144 chambers and tested in running conditions as integral part of the CMS data acquisition, reconstruction, and analysis chain. The deployment of the GEM detector required careful planning throughout the years, posing several challenges of practical and conceptual nature in integrating an entirely new subsystem in the existing CMS frame. Operations on the other hand provided a unique opportunity to test the GEM technology in never-before seen conditions, and an occasion to study their behavior during data taking. In describing some of the solutions to the posed challenges and the findings during the data-taking, the article will focus on the aspects related to power system management, including high-voltage and current monitoring, which is intrinsically related to the response of the chamber due to the workings of the GEM foil charge flow. To this end, this article will illustrate the operations of GE1/1 detectors in the first two years of Run-3, with a particular focus on the analysis of discharge occurrences, on the generation of short circuits in GE1/1 GEM foils and on the adopted mitigation strategies. The applied layout of the GEM detectors is thoroughly described, and detailed operating conditions of the detectors are discussed, along with the actions taken to mitigate these events

The physics case of a 3 TeV muon collider stage

In the path towards a muon collider with center of mass energy of 10 TeV ormore, a stage at 3 TeV emerges as an appealing option. Reviewing the physicspotential of such muon collider is the main purpose of this document. In orderto outline the progression of the physics performances across the stages, a fewsensitivity projections for higher energy are also presented. There are manyopportunities for probing new physics at a 3 TeV muon collider. Some of themare in common with the extensively documented physics case of the CLIC 3 TeVenergy stage, and include measuring the Higgs trilinear coupling and testingthe possible composite nature of the Higgs boson and of the top quark at the 20TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stemfrom the fact that muons are collided rather than electrons. This isexemplified by studying the potential to explore the microscopic origin of thecurrent $g$-2 and $B$-physics anomalies, which are both related with muons.<br

Impact of magnetic field on the stability of the CMS GE1/1 GEM detector operation

The Gas Electron Multiplier (GEM) detectors of the GE1/1 station of the CMS experiment have been operated in the CMS magnetic field for the first time on the 7$^{th}$ of October 2021. During the magnetic field ramps, several discharge phenomena were observed, leading to instability in the GEM High Voltage (HV) power system. In order to reproduce the behavior, it was decided to conduct a dedicated test at the CERN North Area with the Goliath magnet, using four GE1/1 spare chambers. The test consisted in studying the characteristics of discharge events that occurred in different detector configurations and external conditions. Multiple magnetic field ramps were performed in sequence: patterns in the evolution of the discharge rates were observed with these data. The goal of this test is the understanding of the experimental conditions inducing discharges and short circuits in a GEM foil. The results of this test lead to the development of procedure for the optimal operation and performance of GEM detectors in the CMS experiment during the magnet ramps. Another important result is the estimation of the probability of short circuit generation, at 68 % confidence level, p$_{short}$$^{HV}$ $^{OFF}$ = 0.42$^{-0.35+0.94}$% with detector HV OFF and p$_{short}$$^{HV}$ $^{OFF}$ < 0.49% with the HV ON. These numbers are specific for the detectors used during this test, but they provide a first quantitative indication on the phenomenon, and a point of comparison for future studies adopting the same procedure

CAD-based computer vision: the automatic generation of recognition stragtegies

Journal ArticleThree-dimensional model-based computer vision uses geometric models of objects and sensed data to recognize objects in a scene. Likewise, Computer Aided Design (CAD) systems are used to interactively generate three-dimensional models during these fields. Recently, the unification of CAD and vision systems has become the focus of research in the context of manufacturing automation. This paper explores the connection between CAD and computer vision. A method for the automatic generation of recognition strategies based on the geometric properties of shape has been devised and implemented. This uses a novel technique developed for quantifying the following properties of features which compose models used in computer vision: robustness, completeness, consistency, cost, and uniqueness. By utilizing this information, the automatic synthesis of a specialized recognition scheme, called a Strategy Tree, is accomplished. Strategy Trees describe, in a systematic and robust manner. the search process used for recognition and localization of particular objects in the given scene. They consist of selected features which satisfy system constraints and Corroborating Evidence Subtrees which are used in the formation of hypotheses. Verification techniques, used to substantiate or refute these hypotheses, are explored. Experiments utilizing 3-D data are presented