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R. Tschirhart

Publications and source records attributed to R. Tschirhart.

At least 19 recordsLinked to original sources
arXiv2023

Workshop on a future muon program at FNAL

The Snowmass report on rare processes and precision measurements recommended Mu2e-II and a next generation muon facility at Fermilab (Advanced Muon Facility) as priorities for the frontier. The Workshop on a future muon program at FNAL was held in March 2023 to discuss design studies for Mu2e-II, organizing efforts for the next generation muon facility, and identify synergies with other efforts (e.g., muon collider). Topics included high-power targetry, status of R&D for Mu2e-II, development of compressor rings, FFA and concepts for muon experiments (conversion, decays, muonium and other opportunities) at AMF. This document summarizes the workshop discussions with a focus on future R&D tasks needed to realize these concepts.

hep-ex↗
arXiv2019

A Measurement of the Branching Ratio of $π^0$ Dalitz Decay using $K_L \rightarrow π^0π^0π^0$ Decays

We present a measurement of $B(π^0 \rightarrow e^+e^- γ)/B(π^0 \rightarrow γγ)$, the Dalitz branching ratio, using data taken in 1999 by the E832 KTeV experiment at Fermi National Accelerator Laboratory. We use neutral pions from fully reconstructed $K_L$ decays in flight; the measurement is based on about 60 thousand $K_L \rightarrow π^0π^0π^0 \rightarrow γγ~γγ~e^+e^-γ$ decays. We normalize to $K_L \rightarrow π^0π^0π^0 \rightarrow 6γ$ decays. We find $B(π^0 \rightarrow e^+e^- γ)/B(π^0 \rightarrow γγ)$ $(m_{e^+e^-}$ > 15 MeV/$c^2)$ = $[3.920 \pm 0.016(stat) \pm 0.036 (syst)] \times 10^{-3}$. Using the Mikaelian and Smith prediction for the $e^+e^-$ mass spectrum, we correct the result to the full $e^+e^-$ mass range. The corrected result is $B(π^0 \rightarrow e^+e^- γ)/B(π^0 \rightarrow γγ) = [1.1559 \pm 0.0047(stat) \pm 0.0106 (syst)]$%. This result is consistent with previous measurements and the uncertainty is a factor of three smaller than any previous measurement.

hep-ex↗
arXiv2017

Mu2e upgrade physics reach optimization studies for the PIP-II era

The Mu2e experiment at Fermilab is being designed to study the coherent neutrino-less conversion of a negative muon into an electron in the field of a nucleus. This process has an extremely low probability in the Standard Model and its observation would provide unambiguous evidence for BSM physics. The Mu2e design aims to reach a single-event-sensitivity of about $2.5 \times 10^{17}$ and will probe effective new physics mass scales in the 103-104 TeV range, well beyond the reach of the LHC. This work examines the maximum beam power that can be tolerated for beam energies in the 0.5-8 GeV range exploring variations in the geometry in the region of the production target using the MARS15 code. This has implications for how the sensitivity might be further improved with a second generation experiment using an upgraded proton beam from the PIP-II project, which will be capable of providing MW beams to Fermilab experiments later in the next decade.

physics.acc-ph↗
arXiv2016

A Study Of The Energy Dependence Of Radiation Damage In Superconducting Coils For a Next Generation Mu2e At PIP-II

The Mu2e experiment at Fermilab is being designed to study the coherent neutrino-less conversion of a negative muon into an electron in the field of a nucleus. This process has an extremely low probability in the Standard Model, and its observation would provide unambiguous evidence for beyond the standard model physics. The Mu2e design aims to reach a single-event-sensitivity of about $2.5 \times 10^{-17}$ and will probe effective new physics mass scales in the 103-104 TeV range, well beyond the reach of the LHC. This work will examine the maximum beam power that can be tolerated for beam energies in the 0.5-8 GeV range. This has implications for how the sensitivity might be further improved with a second generation experiment using an upgraded proton beam from the PIP-II project, which will be capable of providing MW beams to Fermilab experiments later in the next decade.

physics.acc-ph↗
arXiv2016

Search for the rare decay $K^+\toμ^+ν\barνν$

Evidence of the $K^+\toμ^+ν\barνν$ decay was searched for using E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. The data sample is dominated by the backgrond process $K^+\toμ^+ν_μγ$. An upper limit on the decay rate $Γ(K^+\toμ^+ν\barνν)< 2.4\times 10^{-6}Γ(K^+\to all)$ at 90% confidence level was set assuming the Standard Model muon spectrum. The data are presented in such a way as to allow calculation of rates for any assumed $μ^+$ spectrum.

hep-ex↗
arXiv2015

Search for heavy neutrinos in $K^+\toμ^+ν_H$ decays

Evidence of a heavy neutrino, $ν_H$, in the $K^+\toμ^+ν_H$ decays was sought using the E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. With the major background from the radiative $K^+\toμ^+ν_μγ$ decay understood and suppressed, upper limits (90% C.L.) on the neutrino mixing matrix element between muon and heavy neutrino, $|U_{μH}|^2$, were set at the level of $10^{-7}$ to $10^{-9}$ for the heavy neutrino mass region 175 to 300 MeV/$c^2$.

hep-ex↗
arXiv2014

Status and Opportunities at Project X: A Multi-MW Facility for Intensity Frontier Research

Project X is a multi-megawatt proton facility being developed to support a world-leading program in Intensity Frontier physics at Fermilab. The facility will support programs in elementary particle and nuclear physics, with the potential for broader applications in materials and energy research. Project X is in the development stage with a R&D program focused on front end and superconducting RF acceleration technologies, and with design concepts for a staged implementation. This paper will review the status of the Project X conceptual development and the associated R&D programs.

physics.acc-ph↗
arXiv2013

Report of the Quark Flavor Physics Working Group

This report represents the response of the Intensity Frontier Quark Flavor Physics Working Group to the Snowmass charge. We summarize the current status of quark flavor physics and identify many exciting future opportunities for studying the properties of strange, charm, and bottom quarks. The ability of these studies to reveal the effects of new physics at high mass scales make them an essential ingredient in a well-balanced experimental particle physics program.

hep-ex↗
arXiv2013

Project X: Broader Impacts

Part-3 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". The proposed Project X proton accelerator at Fermilab, with multi-MW beam power and highly versatile beam formatting, will be a unique world-class facility to explore particle physics at the intensity frontier. Concurrently, however, it can also facilitate important scientific research beyond traditional particle physics and provide unprecedented opportunities in applications to problems of great national importance in the nuclear energy and security sector. Part 1 is available as arXiv:1306.5022 [physics.acc-ph] and Part 2 is available as arXiv:1306.5009 [hep-ex].

physics.acc-ph↗
arXiv2013

Precision Neutrino Oscillation Measurements using Simultaneous High-Power, Low-Energy Project-X Beams

The first phase of the long-baseline neutrino experiment, LBNE10, will use a broadband, high-energy neutrino beam with a 10-kt liquid argon TPC at 1300 km to study neutrino oscillation. In this paper, we describe potential upgrades to LBNE10 that use Project X to produce high-intensity, low-energy neutrino beams. Simultaneous, high-power operation of 8- and 60-GeV beams with a 200-kt water Cerenkov detector would provide sensitivity to nu_mu to nu_e oscillations at the second oscillation maximum. We find that with ten years of data, it would be possible to measure sin2(2theta_13) with precision comparable to that expected from reactor antineutrino disappearance and to measure the value of the CP phase, delta_CP, with an uncertainty of (5-10) degrees. This document is submitted for inclusion in Snowmass 2013.

hep-ex↗
arXiv2012

Project X functional requirements specification

Project X is a multi-megawatt proton facility being developed to support a world-leading program in Intensity Frontier physics at Fermilab. The facility is designed to support programs in elementary particle and nuclear physics, with possible applications to nuclear energy research. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions, and to assure that the facility is designed with sufficient upgrade capability to provide U.S. leadership for many decades to come. This paper will briefly review the previously described Functional Requirements, and then discuss their recent evolution.

physics.acc-ph↗
arXiv2012

Project X functional requirements specification

Project X is a multi-megawatt proton facility being developed to support intensity frontier research in elementary particle physics, with possible applications to nuclear physics and nuclear energy research, at Fermilab. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions. This paper will describe the Functional Requirements for the Project X facility and the rationale for these requirements.

physics.acc-ph↗
arXiv2011

Project-X: A new high intensity proton accelerator complext at Fermilab

Fermilab has been working with the international particle physics and nuclear physics communities to explore and develop research programs possible with a new high intensity proton source known as "Project-X". Project X will provide multi-megawatt proton beams from the Fermilab Main Injector over the energy range 60-120 GeV simultaneous with multi-megawatt protons beams at 3 GeV with very flexible beam-timing characteristics and up to 300 kW of pulsed beam at 8 GeV. The Project-X research program includes world leading sensitivity in longbaseline neutrino experiments, neutrino scattering experiments, a rich program of ultra-rare muon and kaon decays, opportunities for next-generation electric dipole moment experiments and other nuclear/particle physics probes that reach far beyond the Standard Model.

hep-ex↗
arXiv2011

Search for the Rare Decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-

The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) < 1.0 x 10^{-10} and Br(KL->pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real.

hep-ex↗
arXiv2010

Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

We present precise tests of CP and CPT symmetry based on the full dataset of K to pipi decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains 16 million K to 2pi0 and 69 million K to pi+pi- decays. We measure the direct CP violation parameter Re(epsilon'/epsilon) = (19.2 pm 2.1)x10-4. We find the KL-KS mass difference Deltam = (5270 pm 12)x10^6 hbar/s and the KS lifetime tauS = (89.62 pm 0.05)x10-12 s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter, epsilon, and the superweak phase, phi_epsilon - phi_SW = (0.40 pm 0.56) degrees. We measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K to pi+pi- (phi+-) and for K to 2pi0 (phi00), Delta phi = (0.30 pm 0.35) degrees. From these phase measurements, we place a limit on the mass difference between K0 and K0bar, DeltaM < 4.8 x 10-19 GeV/c^2 at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.

hep-ex↗
arXiv2009

Study of the decay K+ => pi+,nu,nubar in the momentum region 140<Ppi<199 MeV/c

Experiment E949 at Brookhaven National Laboratory has observed three new events consistent with the decay K+ => pi+,nu,nubar in the pion momentum region 140 < P_pi < 199 MeV/c in an exposure of 1.71e12 stopped kaons with an estimated total background of 0.93+-0.17(stat.)+0.32-0.24(syst.) events. This brings the total number of observed K+ => pi+,nu,nubar events to seven. Combining this observation with previous results, assuming the pion spectrum predicted by the standard model, results in a branching ratio of (1.73+1.15-1.05)e-10. An interpretation of the results for alternative models of the decay K^ => pi+,nothing is also presented.

hep-ex↗