arXiv subjects

F. Porter

Publications and source records attributed to F. Porter.

14 recordsLinked to original sources

arXiv2022

A New Charged Lepton Flavor Violation Program at Fermilab

The muon has played a central role in establishing the Standard Model of particle physics, and continues to provide valuable information about the nature of new physics. A new complex at Fermilab, the Advanced Muon Facility, would provide the world's most intense positive and negative muon beams by exploiting the full potential of PIP-II and the Booster upgrade. This facility would enable a broad muon physics program, including studies of charged lepton flavor violation, muonium-antimuonium transitions, a storage ring muon EDM experiment, and muon spin rotation experiments. This document describes a staged realization of this complex, together with a series of next-generation experiments to search for charged lepton flavor violation.

hep-ex↗

arXiv2019

Mu2e calorimeter readout system

The Mu2e electromagnetic calorimeter is made of two disks of un-doped parallelepiped CsI crystals readout by SiPM. There are 674 crystals in one disk and each crystal is readout by an array of two SiPM. The readout electronics is composed of two types of modules: 1) the front-end module hosts the shaping amplifier and the high voltage linear regulator; since one front-end module is interfaced to one SiPM, a total of 2696 modules are needed for the entire calorimeter; 2) a waveform digitizer provides a further level of amplification and digitizes the SiPM signal at the sampling frequency of $200\ \text{M}\text{Hz}$ with 12-bits ADC resolution; since one board digitizes the data received from 20 SiPMs, a total of 136 boards are needed. The readout system operational conditions are hostile: ionization dose of $20\ \text{krads}$, neutron flux of $10^{12}\ \mathrm{n}(1\ \text{MeVeq})/\text{cm}^2$, magnetic field of $1\ \text{T}$ and in vacuum level of $10^{-4}\ \text{Torr}$. A description of the readout system and qualification tests is reported.

physics.ins-det↗

arXiv2018

The Mu2e calorimeter: quality assurance of production crystals and SiPMs

The Mu2e calorimeter is composed of two disks each containing 1348 pure CsI crystals, each crystal read out by two arrays of 6x6 mm2 monolithic SiPMs. The experimental requirements have been translated in a series of technical specifications for both crystals and SiPMs. Quality assurance tests, on first crystal and then SiPM production batches, confirm the performances of preproduction samples previously assembled in a calorimeter prototype and tested with an electron beam. The production yield is sufficient to allow the construction of a calorimeter of the required quality in the expected times.

physics.ins-det↗

arXiv2018

Quality Assurance on Un-Doped CsI Crystals for the Mu2e Experiment

The Mu2e experiment is constructing a calorimeter consisting of 1,348 undoped CsI crystals in two disks. Each crystal has a dimension of 34 x 34 x 200 mm, and is readout by a large area silicon PMT array. A series of technical specifications was defined according to physics requirements. Preproduction CsI crystals were procured from three firms: Amcrys, Saint-Gobain and Shanghai Institute of Ceramics. We report the quality assurance on crystal's scintillation properties and their radiation hardness against ionization dose and neutrons. With a fast decay time of 30 ns and a light output of more than 100 p.e./MeV measured with a bi-alkali PMT, undoped CsI crystals provide a cost-effective solution for the Mu2e experiment.

physics.ins-det↗

arXiv2018

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.

physics.ins-det↗

arXiv2018

Design and status of the Mu2e crystal calorimeter

The Mu2e experiment at Fermilab searches for the charged-lepton flavour violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive signature of a mono-energetic electron of energy slightly below the muon rest mass (104.967 MeV). The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. Any observation of a CLFV signal will be a clear indication of new physics. The Mu2e detector is composed of a tracker, an electro- magnetic calorimeter and an external veto for cosmic rays surrounding the solenoid. The calorimeter plays an important role in providing particle identification capabilities, a fast online trigger filter, a seed for track reconstruction while working in vacuum, in the presence of 1 T axial magnetic field and in an harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100 MeV electrons and reach at these energies: (a) a time resolution better than 0.5 ns; (b) an energy resolution < 10% and (c) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674 undoped CsI crystals read by two large area arrays of UV-extended SiPMs. We report here the construction and test of the Module-0 prototype. The Module-0 has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati. Preliminary results of timing and energy resolution at normal incidence are shown. A discussion of the technical aspects of the calorimeter engineering is also reported in this paper.

physics.ins-det↗

arXiv2018

Expression of Interest for Evolution of the Mu2e Experiment

We propose an evolution of the Mu2e experiment, called Mu2e-II, that would leverage advances in detector technology and utilize the increased proton intensity provided by the Fermilab PIP-II upgrade to improve the sensitivity for neutrinoless muon-to-electron conversion by one order of magnitude beyond the Mu2e experiment, providing the deepest probe of charged lepton flavor violation in the foreseeable future. Mu2e-II will use as much of the Mu2e infrastructure as possible, providing, where required, improvements to the Mu2e apparatus to accommodate the increased beam intensity and cope with the accompanying increase in backgrounds.

physics.ins-det↗

arXiv2018

The Mu2e crystal calorimeter

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, $\mu^- + Al \to e^- +Al$. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates %\convrate of $\leq 6\ \times\ 10^{-17}$ (@ 90$\%$ C.L.). R$_{\mu e} = \frac{\mu^- + A(Z,N) \to e^- +A(Z,N)}{\mu^- + A(Z,N) \to \nu_{\mu} ^- +A(Z-1,N)} $ of $\leq 6\ \times\ 10^{-17}$ (@ 90$\%$ C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for $\mu \to e \gamma$ decay at MEG as well as the direct searches for new physics at the LHC. The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons ($\sim 10^{10} \mu/$ sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.

physics.ins-det↗

arXiv2018

Design, status and perspective of the Mu2e crystal calorimeter

The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less $\mu \to e$ coherent conversion in the field of an aluminum nucleus. Mu2e will reach a single event sensitivity of about $2.5\cdot 10^{-17}$ that corresponds to four orders of magnitude improvements with respect to the current best limit. The detector system consists of a straw tube tracker and a crystal calorimeter made of undoped CsI coupled with Silicon Photomultipliers. The calorimeter was designed to be operable in a harsh environment where about 10 krad/year will be delivered in the hottest region and work in presence of 1 T magnetic field. The calorimeter role is to perform $\mu$/e separation to suppress cosmic muons mimiking the signal, while providing a high level trigger and a seeding the track search in the tracker. In this paper we present the calorimeter design and the latest R$\&$D results.

physics.ins-det↗

arXiv2018

The Mu2e undoped CsI crystal calorimeter

The Mu2e experiment at Fermilab will search for Charged Lepton Flavor Violating conversion of a muon to an electron in an atomic field. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external system, surrounding the solenoid, to veto cosmic rays. The calorimeter plays an important role to provide: a) excellent particle identification capabilities; b) a fast trigger filter; c) an easier tracker track reconstruction. Two disks, located downstream of the tracker, contain 674 pure CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs. The choice of the crystals and SiPMs has been finalized after a thorough test campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in Frascati. Although the readout electronics were not the final, results show that the current design is able to meet the timing and energy resolution required by the Mu2e experiment.

physics.ins-det↗

arXiv2017

Quality Assurance on a custom SiPMs array for the Mu2e experiment

The Mu2e experiment at Fermilab will search for the coherent $\mu \to e$ conversion on aluminum atoms. The detector system consists of a straw tube tracker and a crystal calorimeter. A pre-production of 150 Silicon Photomultiplier arrays for the Mu2e calorimeter has been procured. A detailed quality assur- ance has been carried out on each SiPM for the determination of its own operation voltage, gain, dark current and PDE. The measurement of the mean-time-to-failure for a small random sample of the pro-production group has been also completed as well as the determination of the dark current increase as a function of the ioninizing and non-ioninizing dose.

physics.ins-det↗

arXiv2017

The calorimeter of the Mu2e experiment at Fermilab

The Mu2e experiment at Fermilab looks for Charged Lepton Flavor Violation (CLFV) improving by 4 orders of magnitude the current experimental sensitivity for the muon to electron conversion in a muonic atom. A positive signal could not be explained in the framework of the current Standard Model of particle interactions and therefore would be a clear indication of new physics. In 3 years of data taking, Mu2e is expected to observe less than one background event mimicking the electron coming from muon conversion. Achieving such a level of background suppression requires a deep knowledge of the experimental apparatus: a straw tube tracker, measuring the electron momentum and time, a cosmic ray veto system rejecting most of cosmic ray background and a pure CsI crystal calorimeter, that will measure time of flight, energy and impact position of the converted electron. The calorimeter has to operate in a harsh radiation environment, in a 10-4 Torr vacuum and inside a 1 T magnetic field. The results of the first qualification tests of the calorimeter components are reported together with the energy and time performances expected from the simulation and measured in beam tests of a small scale prototype.

physics.ins-det↗

arXiv2016

Design and status of the Mu2e electromagnetic calorimeter

The Mu2e experiment at Fermilab aims at measuring the neutrinoless conversion of a negative muon into an electron and reach a single event sensitivity of 2.5x10^{-17} after three years of data taking. The monoenergetic electron produced in the final state, is detected by a high precision tracker and a crystal calorimeter, all embedded in a large superconducting solenoid (SD) surrounded by a cosmic ray veto system. The calorimeter is complementary to the tracker, allowing an independent trigger and powerful particle identification, while seeding the track reconstruction and contributing to remove background tracks mimicking the signal. In order to match these requirements, the calorimeter should have an energy resolution of O(5)% and a time resolution better than 500 ps at 100 MeV. The baseline solution is a calorimeter composed of two disks of BaF2 crystals read by UV extended, solar blind, Avalanche Photodiode (APDs), which are under development from a JPL, Caltech, RMD consortium. In this paper, the calorimeter design, the R&D studies carried out so far and the status of engineering are described. A backup alternative setup consisting of a pure CsI crystal matrix read by UV extended Hamamatsu MPPC's is also presented.

physics.ins-det↗

arXiv2013

The Hot and Energetic Universe: The X-ray Integral Field Unit (X-IFU) for Athena+

The Athena+ mission concept is designed to implement the Hot and Energetic Universe science theme submitted to the European Space Agency in response to the call for White Papers for the definition of the L2 and L3 missions of its science program. The Athena+ science payload consists of a large aperture high angular resolution X-ray optics and twelve meters away, two interchangeable focal plane instruments: the X-ray Integral Field Unit (X-IFU) and the Wide Field Imager (WFI). The X-IFU is a cryogenic X-ray spectrometer, based on a large array of Transition Edge Sensors (TES), offering 2.5 eV spectral resolution, with ~5" pixels, over a field of view of 5 arc minutes in diameter. In this paper, we briefly describe the Athena+ mission concept and the X-IFU performance requirements. We then present the X-IFU detector and readout electronics principles, the current design of the focal plane assembly, the cooling chain and review the global architecture design. Finally, we describe the current performance estimates, in terms of effective area, particle background rejection, count rate capability and velocity measurements. Finally, we emphasize on the latest technology developments concerning TES array fabrication, spectral resolution and readout performance achieved to show that significant progresses are being accomplished towards the demanding X-IFU requirements.

astro-ph.IM↗