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All sources NASA NTRS DOE OSTI

DOE OSTI2022

Development and construction status of the Mu2e electromagnetic calorimeter mechanical structures

Abstract The Mu2e experiment at Fermilab will search for the CLFV neutrino-less coherent conversion of a muon into an electron in the field of an aluminum nucleus. The observation of this process would be the evidence of physics beyond the Standard Model. Mu2e comprises a straw-tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter provides electron identification, a fast trigger and aids track reconstruction. It is a state-of-the-art crystal calorimeter and employs 1340 pure CsI crystals readout by UV-extended SiPM and fast electronics. The design consists of two identical annular disks positioned at the relative distance of 70 cm downstream the target.The hostile Mu2e conditions (total ionizing dose of 12 krad and a neutron fluence of 5 × 10 10 n/cm 2 @ 1 MeVeq (Si)/y, 1 T magnetic field and vacuum level of 10 −4 Torr) posed tight constraints on the mechanical structures and materials choice. The support structure of the two crystal matrices employs two aluminum hollow rings and parts made of open-cell vacuum-compatible carbon fiber. SiPMs and front-end electronics for each crystal are assembled in one mechanical unit inserted in a machined copper holder. The units are supported by a plate made of vacuum-compatible material. The plate integrates the cooling system made of a network of copper lines flowing a low temperature fluid and placed in thermal contact with the copper holders. The DAQ is hosted in aluminum crates positioned on the lateral surface of the disks. The crates also integrate the DAQ electronics cooling system. We review the constraints on the calorimeter structures design, the development of all the structural components, including the simulations that have determined the materials and technological choices and the specifications of the cooling station, components production and quality assurance tests, the procedures for detector assembly, transportation and installation in the experimental area.

Instruments & Instrumentation↗

DOE OSTI2024

One-dimensional mapping of femtosecond laser filaments using coherent microwave scattering

Here, this paper reports on the use of coherent microwave scattering (CMS) for spatially resolved electron number density measurements of elongated plasma structures induced at mid-IR femtosecond filamentation in air. The presented studies comprise one-dimensional mapping of laser filaments induced via 3.9 µm, 127.3 fs laser pulses at output energies up to 15 mJ. The axial electron number density was measured to be invariant (about 2 × 10 15 c⁢m −3 ) along the entire filament length and for all tested laser pulse energies 5–15 mJ, and the corresponding laser intensity in the middle portion of the filament was estimated to be nearly constant for 5–15 mJ pulse energies (about 30−40 TW/c⁢m 2 ). These findings support that intensity clamping conditions were achieved in the experiments. The proposed approach enables capabilities that are currently unavailable to perform absolute and longitudinally resolved measurements of electron number density in laser filaments and to precisely characterize conditions associated with self-focusing and intensity clamping.

plasma diagnostic techniques↗

DOE OSTI2024

Wave-packet manipulation of He Rydberg states by a seeded free-electron laser

We report a two-dimensional pump-control-probe spectroscopic study of the dynamics of singly excited He Rydberg-state wave packets with a seeded extreme ultraviolet (XUV) free-electron laser (FEL) source. A pair of coherent XUV pulses, defined by their coarse time separation and relative phase, created and manipulated the wave packets. The He atoms were postionized by infrared (IR) pulses, and the ion yield was measured as a function of XUV phase and IR arrival time. We tagged and sorted the relative phase of the XUV pulse pair on a single-shot basis by fitting each FEL spectrum with a suitable function that accounts for nonidealities of the XUV pulse pairs, associated with the seeding process; more generally, the fit returns the time-dependent electric field of the FEL spectra. The experimental two-dimensional maps of ion yields, measured as a function of IR (probe) delay and of XUV (pump-control) phase, were compared with the solution of the first-order time-dependent Schrödinger equation for this field. Despite the fact that the experimental conditions imply strong excitation, beyond the approximations of first-order perturbation theory, the simulated map satisfactorily reproduces the experimental one for temporally well-separated pulses. We show that by selecting data at appropriate values of pump-control phase, we enhance or suppress the amplitude of chosen wave-packet components consisting of two or more Rydberg states. When the temporal overlap of the pulse pair cannot be neglected, the phase reconstruction is underdetermined, and we provide a simplified comparison between data and simulations. Published by the American Physical Society 2024

Dumergue, Mathieu (ORCID:0000000236984406)↗

DOE OSTI2026

Development of a pattern recognition algorithm for reconstructing multi-particle events in the Mu2e detector

Mu2e is an upcoming experiment at Fermilab and its main goal is to search for the Charged Lepton Flavor Violation (CLFV) in the coherent transition of a muon into an electron on an Al target. In Mu2e, multi-particle events can occur simultaneously within the same time region and it is crucial to accurately identify each particle track, including signals, to improve the robustness of track finding methods and enhance reconstruction efficiency. ¯p annihilation is one of the background events and produces multiple particles that can mimic signal events. Additionally, photons from radiative pion captures can produce a γ → $e+e−$ pair, which can be used to calibrate the Mu2e momentum scale and the resolution. The Mu2e track reconstruction sequence begins by grouping hits produced in the tracker based on time and z coordinate information, called TimeCluster, and selected hits are processed to reconstruct helices and determine their momentum. The current pattern recognition algorithms identify a single helix per TimeCluster for single track events. A new pattern recognition algorithm is being developed to reconstruct multi-particle events and its features for finding multiple tracks and the current evaluation results are reported.

Kitagawa, H. [Pisa U.]↗

DOE OSTI2021

Observation of Polarization-Dependent Changes in Higher-Order Mode Responses as a Function of Transverse Beam Position in Tesla-Type Cavities at FAST

Higher-order modes (HOMs) in superconducting rf cavities present problems for an electron bunch traversing the cavity in the form of long-range wakefields from previous bunches. These may dilute the emittance of the macropulse average, especially with low emittance beams at facilities such as the European X-ray Free-electron Laser (XFEL) and the upgraded Linac Coherent Light Source (LCLS-II). Here we present observations of HOMs driven by the beam at the Fermilab Accelerator Science and Technology (FAST) facility. The FAST facility features two independent TESLA-type cavities (CC1 and CC2) after a photocathode rf gun followed by an 8-cavity cryomodule. The HOM signals were acquired from cavities using bandpass filters of 1.75 ± 0.15 GHz, 2.5 ± 0.2 GHz, and 3.25 ± 0.2 GHz and recorded using an 8-GHz, 20 GSa/s oscilloscope. The frequency resolution obtained is sufficient to separate polarization components of many of the HOMs. These HOM signals were captured from CC1 and cavities 1 and 8 of the cryomodule for various initial trajectories through the cavities, and we observe correlations between trajectory, HOM signals, and which polarization component of a mode is affected.

Thurman-Keup, Randy Michael↗

DOE OSTI2020

Atomistic Studies of Individual Impurities and Impurity Complexes in III-V Semiconductors. Final report

The central hypothesis of our investigation is that reduced symmetries significantly influence the properties of individual impurities and impurity complexes in semiconductors. To disentangle the properties of the local environments of these impurities and impurity complexes from the behavior of an ensemble of impurities, at U. Iowa we performed theoretical calculations of specific local environments and developed the theoretical technology to calculate spin and charge transport through those local environments, in which the contact is a localized probe (scanning tunneling microscopy tip). These calculations were designed to be brought into comparison with experimental measurements made by Prof. Gupta’s group at Ohio State University. The principal environment that we focused on is the (110) surface of GaAs and other III-V semiconductors, because pristine surfaces can be revealed through a natural cleavage plane. We studied how the p-d hybridization of transition-metal dopants is influenced by the energetic location and the local environment’s symmetry-breaking of the d levels, and how the 4f-shell states of rare earth impurities couple to the surroundings. We calculated long-distance properties using tight-binding (linear combination of atomic orbitals, LCAO) Green’s function methods. The spin character of the dopants is often coherent on the time-scale of electronic transport through the region, and so correlations of the spin character of a dopant with that of a spinpolarized STM tip, or another dopant in the vicinity, can influence the measured conductivity from STM. We constructed a robust theory for these effects that can be used to describe quantitatively the measurements made by spin-polarized STM.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

Transversely driven coherent beam oscillations and specifications for high-frequency ESR dipole power supply current ripple

We study coherent transverse beam oscillations in the EIC electron storage ring (ESR), to specify the tolerance for high-frequency ripple of the dipole magnet power supplies. To avoid unacceptable proton emittance growth from the oscillating beam-beam kick from the electrons, the amplitude of these oscillations at the proton betatron frequency needs to be limited to about 1e-4 fraction of the beam size at the interaction point. We show that the oscillations potentially caused by the ESR magnet dipole power supply ripple could be substantial, but still tolerable, if we account for the eddy current shielding in the vacuum chamber.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

Slow control and data acquisition systems in the Mu2e experiment

The Mu2e experiment at the Fermilab Muon Campus will search for the coherent neutrinolessconversion of a muon into an electron in the field of an aluminum nucleus with a sensitivityimprovement by a factor of 10,000 over existing limits. The Mu2e Trigger and Data AcquisitionSystem (TDAQ) usesotsdaqas the online Data Acquisition System (DAQ) solution. Developed atFermilab,otsdaqintegrates both theartdaqDAQ and theartanalysis frameworks for event transfer,filtering, and processing.otsdaqis an online DAQ software suite with a focus on flexibility andscalability and provides a multi-user, web-based, interface accessible through a web browser. Thedata stream from the detector subsystems is read by a software filter algorithm that selects eventswhich are combined with the data flux coming from a Cosmic Ray Veto System. The DetectorControl System (DCS) has been developed using the Experimental Physics and Industrial ControlSystem (EPICS) open source platform for monitoring, controlling, alarming, and archiving. TheDCS System has been integrated intootsdaq. A prototype of the TDAQ and the DCS systems hasbeen built at Fermilab’s Feynman Computing Center. In this paper, we report on the progress ofthe integration of this prototype in the onlineotsdaqsoftware.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Online DAQ and slow control interface for the Mu2e experiment

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

Crystal Calorimetry for Charged Lepton Flavor Violation Searches

The Mu2e experiment at Fermilab aims to search for Charged Lepton Flavor Violation (CLFV) through the coherent conversion of a muon into an electron in the field of an aluminum nucleus. This process, highly suppressed in the Standard Model, would clearly indicate new physics if observed. A crucial component of Mu2e is its electromagnetic calorimeter, which enhances the identification and measurement of conversion electrons. The calorimeter consists of two disks of undoped CsI crystals read out by custom-designed SiPMs and fast front-end electronics. This paper presents an overview of the calorimeter’s design, its custom SiPM technology, the readout and data acquisition system, and the results from commissioning tests.Building on the experience from Mu2e, the proposed Mu2e-II upgrade aims to enhance further the experiment’s sensitivity by an order of magnitude. This requires significant advancements in calorimeter technology, particularly in crystal materials and photodetector performance. Studies on BaF$_2$ and LYSO crystals, as well as the development of radiation-hard Silicon Photomultipliers (SiPMs), are currently underway. Test beam results demonstrate promising improvements in energy resolution and timing capabilities, ensuring the feasibility of next-generation calorimetry solutions for Mu2e-II.

Atanov, N. [Dubna, JINR]↗

NASA NTRS1972

Coherent Optical Processing of Phased Array Radar Data

Interfacing a coherent optical processor, which utilizes an electron-beam addressed, potassium dideuterium phosphate (KDP) crystal modulator, with a linear phased array is studied. An abbreviated development of typical radar signals from a linear array is included. A plan for formating the spatial modulator with linear array signals is presented. The theoretical expectations which include target angle and Doppler are derived. A simulated set of M signals which are typical of a linear array of M elements was devised. This set of signals was used to modulate the wave front of collimated laser light via the KDP crystal according to the format presented.

Rogers, J. W.↗

NASA NTRS1981

Auroral kilometric radiation - A theoretical review

Auroral kilometric radiation (AKR) is a high-density radio wave radiation in the frequency band from 50 to 750 kHz, with a peak around 250 kHz, that has been observed emanating from the auroral zone. In connection with its low frequency, the radiation can not penetrate through the ionosphere to earth, so all observations have been made by satellite. The AKR is closely correlated with the occurrence of discrete auroral arcs, which are believed to be generated by intense inverted V electron precipitation bands. A review is presented of several theories which have been proposed to explain the observed AKR. Attention is given to the conversion of electron cyclotron wave to O mode, the coherent amplification of gyroemission by velocity space instabilities, beam-driven electromagnetic instability via low-frequency turbulence, soliton radiation, loss cone instability, nonlinear beating of electrostatic waves, and the beam amplification of electromagnetic wave via coherent EIC density fluctuations.

Grabbe, C. L.↗

NASA NTRS1990

Magnetism and superconductivity of some Tl-Cu oxides

Many copper oxide based Thallium compounds have now been discovered. In comparison to the Bi-compounds, the Tl-system shows a richer diversity; viz., High Temperature Superconductors (HTSC) can be obtained with either one or two Tl-0 layers (m = 1,2); also, the triple-digit phases are easier to synthesize. The value of d, oxygen stoichiometry, is critical to achieving superconductivity. The Tl system is robust to oxygen loss; Tl may be lost or incorporated by diffusion. A diffusion coefficient equal to 10 ms at 900 C was determined. Both ortho-rhombic and tetragonal structures are evidenced, but HTSC behavior is indifferent to the crystal symmetry. This system has the highest T(sub c) confirmed. T(sub c) generally increases with p, the number of CuO layers, but tends to saturate at p = 3. Zero resistance as high as 125K has been observed. Most of these HTSC's are hole type, but the Ce-doped specimens may be electronic. The magnetic aspects were studied; because in addition to defining the perfectly diamagnetic ground state as in the conventional superconductors, magnetism of the copper oxides show a surprising variety. This is true of both the normal and the superconducting states. Also, due to the large phonon contribution to the specific heat at the high T(sub c) accurate thermal measurement of important parameters such as the sp. heat jump, electronic density of states, D(Ef) and coherence length are uncertain, and thus, are estimated from the magnetic results. Results from the Tl-system CuO, LaBaCuO, 120 and the Bi-CuO compounds are discussed. The emphasis is on the role of magnetism in the TlCuO HTSC, but technological aspects are also pointed out.

Datta, Timir↗

NASA NTRS1991

Magnetism and superconductivity of some Tl-Cu oxides

Many copper oxide based Thallium compounds are now known. In comparison to the Bi-compounds, the Tl-system shows a richer diversity; i.e., High Temperature Superconductors (HTSC) can be obtained with either one or two Tl-0 layers (m = 1,2); also, the triple-digit phases are easier to synthesize. The value of d, oxygen stoichiometry, is critical to achieving superconductivity. The Tl system is robust to oxygen loss; Tl may be lost or incorporated by diffusion. A diffusion coefficient equal to 10 ms at 900 C was determined. Both ortho-rhombic and tetragonal structures are found, but HTSC behavior is indifferent to the crystal symmetry. This system has the highest T(sub c) confirmed. T(sub c) generally increases with p, the number of CuO layers, but tends to saturate at p = 3. Zero resistance was observed at temperatures as great as 125 K. Most of these HTSC's are hole type, but the Ce-doped specimens may be electronic. The magnetic aspects were studied; because in addition to defining the perfectly diamagnetic ground state as in conventional superconductors, magnetism of the copper oxides show a surprising variety. This is true of both the normal and the superconducting states. Also, due to the large phonon contribution to the specific heat at the high T(sub c) jump, electronic density of states, D(Ef), and coherence length are uncertain, and thus, are estimated from the magnetic results. Results from the Tl-system CuO, LaBaCuO,120 and the Bi-CuO compounds are discussed. The emphasis is on the role of magnetism in the Tl-CuO HTSC, but technological aspects are also pointed out.

Datta, Timir↗

NASA NTRS2016

Outer Radiation Belt Dropout Dynamics Following the Arrival of Two Interplanetary Coronal Mass Ejections

Magnetopause shadowing and wave-particle interactions are recognized as the two primary mechanisms for losses of electrons from the outer radiation belt. We investigate these mechanisms, sing satellite observations both in interplanetary space and within the magnetosphere and particle drift modeling. Two interplanetary shocks sheaths impinged upon the magnetopause causing a relativistic electron flux dropout. The magnetic cloud (C) and interplanetary structure sunward of the MC had primarily northward magnetic field, perhaps leading to a concomitant lack of substorm activity and a 10 day long quiescent period. The arrival of two shocks caused an unusual electron flux dropout. Test-particle simulations have shown 2 to 5 MeV energy, equatorially mirroring electrons with initial values of L 5.5can be lost to the magnetosheath via magnetopause shadowing alone. For electron losses at lower L-shells, coherent chorus wave-driven pitch angle scattering and ULF wave-driven radial transport have been shownto be viable mechanisms.

Alves, L. R.↗

DOE OSTI2022

The MU2E Experiment at FERMILAB: R&D, Design and Status

The Mu2e Experiment at Fermilab 1) will search for coherent, neutrinoless conversion of negative muons into electrons in the field of an aluminum nucleus, µ - + N (A, Z) → e - + N (A, Z). This is an example of Charged Lepton Flavour Violation (CLFV) never observed experimentally. The dynamics of such a process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass (~104.967 MeV). If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between conversion and capture rate R µe ≤ 6 × 10 -17 (@ 90% C.L.). This will improve the current limit of a factor of 10 4 over previous experiments. The experiment complements and extends the current/planned searches (µ → eγdecay at MEG , mu3e) as well as the direct searches for new physics at the LHC. Indeed, such CLFV searches in the muon sector probe new physics at a mass scale inaccessible with direct searches at either present or planned high-energy colliders. To detect the muon conversion process, a very intense pulsed beam of negative muons is produced by means of a S-shape Superconducting Solenoid Magnet System that is organized into three subsystems: the Production Solenoid, the Transport Solenoid and the Detector Solenoid. The beam is stopped at 10 GHz on an Aluminum target inside the Detector Solenoid. The Mu2e detectors, also installed inside the Detector Solenoid, are a high-precision tracker made on ~20000 straw tubes, and a calorimeter composed of ~1500 pure CsI crystals organized in two disks and readout by two large area UV-extended Silicon Photomultipliers (SiPMs). The Detector Solenoid region is surrounded by a Cosmic Ray Veto based on scintillators readout by SiPMs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2026

Electronic Origin of Delicate Antiferromagnetism in Fe 𝑥 ⁢NbS 2

Among the family of intercalated transition-metal dichalcogenides (TMDs), Fe 𝑥 ⁢NbS 2 is found to possess unique current-induced resistive switching behaviors, tunable antiferromagnetic states, and a commensurate charge order, all of which are tied to a critical Fe doping of 𝑥 𝑐 = 1/3. However, the electronic origin of such extreme stoichiometry sensitivities remains unclear. Combining angle-resolved photoemission spectroscopy (ARPES) with density functional theory (DFT) calculations, we identify and characterize a dramatic eV-scale electronic restructuring that occurs across the 𝑥𝑐. Moment-carrying Fe 3⁢𝑑 𝑧 2 electrons manifest as narrow bands within 200 meV of the Fermi level, distinct from other transition metal intercalated TMD magnets. These states strongly hybridize with itinerant electrons in the TMD layer and rapidly lose coherence above 𝑥 𝑐 due to correlation-driven effects. This sudden quasiparticle decoherence collapses the Fe-Nb hybridization, which explicitly suppresses the out-of-plane effective Fe-Fe exchange interaction, driving the transformation of the magnetic ground state from an antiferromagnetic stripe phase to a zigzag phase. Furthermore, these observations resemble the exceptional electronic and magnetic sensitivity of strongly correlated systems, and demonstrate that quantifying orbital-specific hybridization via ARPES offers an alternative pathway to evaluate effective magnetic exchange in metallic magnets, complementing inelastic neutron and resonant x-ray scattering probes.

Angle-resolved photoemission spectroscopy↗

DOE OSTI2022

Molecular qubits based on photogenerated spin-correlated radical pairs for quantum sensing

Photogenerated spin-correlated radical pairs (SCRPs) in electron donor–bridge–acceptor (D–B–A) molecules can act as molecular qubits and inherently spin qubit pairs. SCRPs can take singlet and triplet spin states, comprising the quantum superposition state. Their synthetic accessibility and well-defined structures, together with their ability to be prepared in an initially pure, entangled spin state and optical addressability, make them one of the promising avenues for advancing quantum information science. Coherence between two spin states and spin selective electron transfer reactions form the foundation of using SCRPs as qubits for sensing. We can exploit the unique sensitivity of the spin dynamics of SCRPs to external magnetic fields for sensing applications including resolution-enhanced imaging, magnetometers, and magnetic switch. Molecular quantum sensors, if realized, can provide new technological developments beyond what is possible with classical counterparts. While the community of spin chemistry has actively investigated magnetic field effects on chemical reactions via SCRPs for several decades, we have not yet fully exploited the synthetic tunability of molecular systems to our advantage. This review offers an introduction to the photogenerated SCRPs-based molecular qubits for quantum sensing, aiming to lay the foundation for researchers new to the field and provide a basic reference for researchers active in the field. We focus on the basic principles necessary to construct molecular qubits based on SCRPs and the examples in quantum sensing explored to date from the perspective of the experimentalist.

Mani, Tomoyasu (ORCID:0000000241255195)↗