Search

This paper reports on the design and construction of a High Voltage Distribution System (HVDS) for a “Smart Switch” developed to provide high voltage (HV) to a series of stacked straw detector planes in the Mu2e Electron Tracking Detector (ETD). Each plane is composed of three 120 deg. Crescent-shaped panels, and each panel is composed of 96 straw tubes. The HVDS provides HV on-off, current monitoring, recording, and crowbar for over-current protection. The inter-communication system is based on TCP/IP. The HVDS supplies HV with long term stability, and accurately monitors the applied voltage and currents.

We present a measurement of B(π0→e+e-γ)/B(π0→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 KL decays in flight; the measurement is based on ∼60 thousand KL→π0π0π0→γγγγe+e-γ decays. We normalize to KL→π0π0π0→6γ decays. We find B(π0→e+e-γ)/B(π0→γγ) (me+e->15 MeV/c2)=[3.920±0.016(stat)±0.036(syst)]×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(π0→e+e-γ)/B(π0→γγ)=[1.1559±0.0047(stat)±0.0106(syst)]%. This result is consistent with previous measurements, and the uncertainty is a factor of 3 smaller than any previous measurement.

This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron-antineutron oscillations, and suggests avenues for future improvement in the experimental sensitivity., Comment: Submitted to Physics Reports

Report of the first workshop to identify approaches and techniques in the domain of quantum sensing that can be utilized by future High Energy Physics applications to further the scientific goals of High Energy Physics.

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.

Advances in high intensity beams have driven particle physics forward since the inception of the field. State-of-the-art and next generation high intensity beams will drive experiments searching for ultrarare processes sensitive through quantum corrections to new particle states far beyond the reach of direct production in foreseeable beam colliders. The recent discovery of the ultrarare B meson decay Bs → μμ, with a branching fraction of 3 × 10-9 for example, has set stringent limits on new physics within direct reach of the Large Hadron Collider. Today, even in the context of the Higgs boson discovery, observation of finite neutrino masses is the only laboratory evidence of physics beyond the Standard Model of particle physics. The tiny mass scale of neutrinos may foretell and one day expose physics that connects quarks and leptons together at the "grand unification" scale and may be the portal through which our world came to the matter-dominated state so different from conditions we expect in the early universe. Here we describe next generation neutrino and rare processes experiments that will deeply probe these and other questions central to the field of particle physics.

Evidence of the ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\nu}$ decay was searched for using E949 (Brookhaven National Laboratory, USA) experimental data with an exposure of $1.70\ifmmode\times\else\texttimes\fi{}1{0}^{12}$ stopped kaons. The data sample is dominated by the background process ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\gamma}$. An upper limit on the decay rate $\mathrm{\ensuremath{\Gamma}}({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\nu})l2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\mathrm{\ensuremath{\Gamma}}({K}^{+}\ensuremath{\rightarrow}\text{all})$ 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 ${\ensuremath{\mu}}^{+}$ spectrum.

The Mu2e experiment endeavors to search for the coherent decay of a muon to an electron in the Coulomb field of a nucleus with an expected sensitivity of R μ e 6 × 10 − 17 , at the 90% confidence level. This process is sensitive to many new physics scenarios beyond the standard model. Mu2e has received strong support from Fermilab and the US funding agencies, and is projected to begin data taking in 2017.

Evidence of a heavy neutrino, ν H , in the K + → μ + ν H decays was sought using the E949 experimental data with an exposure of 1.70 × 1 0 12 stopped kaons. With the major background from the radiative K + → μ + ν μ γ decay understood and suppressed, upper limits (90% C.L.) on the neutrino mixing matrix element between the muon and heavy neutrinos, | U μ H | 2 , were set at the level of 1 0 - 7 to 1 0 - 9 for the heavy neutrino mass region 175 to 300 MeV / c 2 .

We have searched for the K{sup +} {yields} {pi}{sup +}{gamma}{gamma} decay in the kinematic region with {pi}{sup +} momentum close to the end point. No events were observed, and the 90% confidence-level upper limit on the partial branching ratio was obtained, B(K{sup +} {yields} {pi}{sup +}{gamma}{gamma}, P > 213 MeV/c) < 8.3 x 10{sup -9} under the assumption of chiral perturbation theory including next-to-leading order ''unitarity'' corrections. The same data were used to determine an upper limit on the K{sup +} {yields} {pi}{sup +}{gamma} branching ratio of 2.3 x 10{sup -9} at the 90% confidence level.

Fermilab experiment E921, or Charged Kaons at the Main Injector (CKM), will measure the branching ratio of the ultrarare kaon decay: K/sup +//spl rarr//spl pi//sup +//spl nu//spl nu/. To do this, CKM will need to reject the far more copious decay K/sup +//spl rarr//spl pi//sup +//spl pi//sup 0//spl rarr//spl pi//sup +//spl gamma//spl gamma/ by a factor of more than 10 billion. Much of this rejection will come from the detection of either or both of the photons by our photon veto system. The main CKM photon veto system is based on 80-layer sandwiches of 1-mm Pb and 5-mm fast scintillator with wavelength shifting fibers inside a vacuum decay volume, read out with photomultiplier tubes outside the vacuum. We describe the design of the CKM photon veto system and the testing of a prototype in an electron beam at Jefferson National Laboratory, demonstrating an order of magnitude better performance than the required 3/spl times/10/sup -5/ inefficiency for a 1 GeV electromagnetic shower.

Results of the November 2000 test run of the prototype MVS system are described. The muon rejection factor at the level of 6.0×10 −6 has been achieved with pion detection efficiency near 87%.

The high precision measurement of the ultra-rare K + → π + ν ν ¯ decay at Fermilab would be one of the most incisive probes of quark flavor physics this decade. The dramatic physics reach of a precision measurement of K + → π + ν ν ¯ is due to three factors. 1) The Standard Model prediction for the K + → π + ν ν ¯ and K L 0 → π 0 ν ν ¯ branching fractions are broadly recognized as theoretically robust to the 2-4% level. No other loop-dominated quark process can be predicted with this level of certainty. 2) The K + → π + ν ν ¯ branching fraction is highly suppressed in the Standard Model to the level of less than 1 part in 10 billion. This suppression allows physics beyond the Standard Model to contribute noticeably to the branching fraction with enhancements of up to factors of 5 above the Standard Model level. 3) The certainty with which the Standard Model contribution to K + → π + ν ν ¯ is known permits a 5 σ discovery potential for new physics even for enhancements of the branching fraction as small as 20%. This sensitivity is unique in quark flavor physics and probes essentially all models of new physics that couple to quarks within the reach of the LHC. Further, precision measurement of K + → π + ν ν ¯ is sensitive to many models of new physics far beyond the direct mass reach of the LHC. The experimental challenge of measuring K + → π + ν ν ¯ at the 1 in 10-billion Standard Model rate has been met successfully. Several events of the K + → π + ν ν ¯ process have been clearly observed at BNL. Operating the Tevatron after Run-II as a 120 GeV high-duty factor synchrotron “Stretcher” offers the opportunity to reach more than two orders of magnitude greater sensitivity yielding a 1000-event experiment based on incremental improvements to the techniques refined and firmly demonstrated at BNL. The Fermilab Stretcher would be a unique facility that would provide ideal properties for such rare-decay experiments, allowing the demonstrated performance of the AGS experiment to be extrapolated with confidence to an experiment driven by the Fermilab Stretcher.

We observe 441 K(L)-->e(+)e(-)e(+)e(-) candidate events with a background of 4.2 events and measure B(K(L)-->e(+)e(-)e(+)e(-)) = [3.72+/-0.18(stat)+/-0.23(syst)]x10(-8) in the KTeV/E799II experiment at Fermilab. Using the distribution of the angle between the planes of the e(+)e(-) pairs, we measure the CP parameters beta(CP) = -0.23+/-0.09(stat)+/-0.02(syst) and gamma(CP) = -0.09+/-0.09(stat)+/-0.02(syst). We also present the first detailed study of the e(+)e(-) invariant mass spectrum in this decay mode.

We have studied the rare weak radiative hyperon decay Xi degrees -->Sigma degrees gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Xi degrees -->Lambdapi degrees decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of B(Xi degrees -->Sigma degrees gamma)/B(Xi degrees -->Lambdapi degrees ) = (3.34+/-0.05+/-0.09)x10(-3). By analyzing the final state decay distributions, we have also determined that the Sigma degrees emission asymmetry parameter for this decay is alpha(XiSigma) = -0.63+/-0.09.

We have perfomed studies of the ${K}_{L}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ direct emission ( $\mathrm{DE}$) and inner Bremsstrahlung ( $\mathrm{IB}$) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find ${a}_{1}/{a}_{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.737\ifmmode\pm\else\textpm\fi{}0.034{\mathrm{GeV}}^{2}$ for the $\mathrm{DE}$ form-factor parameter in the $\ensuremath{\rho}$-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure $\ensuremath{\Gamma}({K}_{L}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}{,E}_{\ensuremath{\gamma}}^{*}g20\mathrm{MeV})/\ensuremath{\Gamma}({K}_{L}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(20.8\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, and a ${K}_{L}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ $\mathrm{DE}/(\mathrm{DE}+\mathrm{IB})$ branching ratio of $0.683\ifmmode\pm\else\textpm\fi{}0.011$.

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)

The modern trigger and data acquisition systems that instrument discovery experiments at the Large Hadron Collider (LHC) at CERN are very complex digital systems that select, reduce, and process enormous volumes of data in real-time to match the resources of state-of-the-art distributed computing available to researchers. Never before in particle physics have such powerful digital reconstruction and filtering systems been matched to a world-wide distributed system of computing of unprecedented scale. The goal of these massive aggregate computing systems is to extract as much physical information as possible from collision events at the LHC with well understood selection criteria and biases. Current strategies and future challenges in providing these aggregate real-time and offline computing systems are described.

We present results of a search for a new form of hadronic matter, a six-quark, dibaryon state called the ${H}^{0}$, a state predicted to exist in several theoretical models. Analyzing data collected by experiment E799-II at Fermilab, we searched for the decay ${H}^{0}\ensuremath{\rightarrow}\ensuremath{\Lambda}p{\ensuremath{\pi}}^{\ensuremath{-}}$ and found no candidate events. We place an upper limit on $[B({H}^{0}\ensuremath{\rightarrow}\ensuremath{\Lambda}p{\ensuremath{\pi}}^{\ensuremath{-}})d{\ensuremath{\sigma}}_{H}/d\ensuremath{\Omega}]/(d{\ensuremath{\sigma}}_{\ensuremath{\Xi}}/d\ensuremath{\Omega})$ and, in the context of published models, exclude the region of lightly bound mass states just below the $\ensuremath{\Lambda}\ensuremath{\Lambda}$ mass threshold, $2.194l{M}_{H}l2.231\mathrm{GeV}/{c}^{2}$, with lifetimes from $\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\mathrm{sec}$ to $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\mathrm{sec}$.

We report the first observation of a manifestly CP violating effect in the K{sub L}{yields}{pi}{sup +}{pi}{sup -}e{sup +}e{sup -} decay mode. A large asymmetry was observed in the distribution of these decays in the CP -odd and T -odd angle {phi} between the decay planes of the e{sup +}e{sup -} and {pi}{sup +}{pi}{sup -} pairs in the K{sub L} center of mass system. After acceptance corrections, the overall asymmetry is found to be [13.6{+-}2.5(stat){+-}1. 2(syst)]% . This is the largest CP -violating effect yet observed when integrating over the entire phase space of a mode and the first such effect observed in an angular variable. (c) 2000 The American Physical Society.

We report on a new measurement of the decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ by the KTeV experiment at Fermilab. We determine the ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ branching ratio to be $(1.68\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.08)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. Our data show the first evidence for a low-mass $\ensuremath{\gamma}\ensuremath{\gamma}$ signal as predicted by recent $O({p}^{6})$ chiral perturbation calculations which include vector meson exchange contributions. From our data, we extract a value for the effective vector coupling ${a}_{V}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.72\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.06$.

Author(s): Alavi-Harati, A; Albuquerque, IF; Alexopoulos, T; Arenton, M; Arisaka, K; Averitte, S; Barker, AR; Bellantoni, L; Bellavance, A; Belz, J; Ben David, R; Bergman, DR; Blucher, E; Bock, GJ; Bown, C; Bright, S; Cheu, E; Childress, S; Coleman, R; Corcoran, MD; Corti, G; Cox, B; Crisler, MB; Erwin, AR; Ford, R; Glazov, A; Golossanov, A; Graham, G; Graham, J; Hagan, K; Halkiadakis, E; Hanagaki, K; Hidaka, S; Hsiung, YB; Jejer, V; Jennings, J; Jensen, DA; Kessler, R; Kobrak, HGE; La Due, J; Lath, A; Ledovskoy, A; Mc Bride, PL; Mc Manus, AP; Mikelsons, P; Monnier, E; Nakaya, T; Nauenberg, U; Nelson, KS; Nguyen, H; O’dell, V; Pang, M; Pordes, R; Prasad, V; Qiao, C; Quinn, B; Ramberg, EJ; Ray, RE; Roodman, A; Sadamoto, M; Schnetzer, S; Senyo, K; Shanahan, P; Shawhan, PS; Slater, W; Solomey, N; Somalwar, SV; Stone, RL; Suzuki, I; Swallow, EC; Swanson, RA; Taegar, SA; Tesarek, RJ; Thomson, GB; Toale, PA; Tripathi, A; Tschirhart, R; Wah, YW; Wang, J; White, HB; Whitmore, J; Winstein, B; Winston, R; Wu, JY; Yamanaka, T | Abstract: We have compared the decay rates of KL and KS toΠ+ Π- Π0Π0 final states using a subset of the data from the KTeV experiment (E832) at Fermilab. We find that the direct-CP-violation parameter Re (μ’/μ) is equal to [28.0±3.0(stat)±2.8(syst)]×10-4. This result definitively establishes the existence of CP violation in a decay process. © 1999 The American Physical Society.

We report on a search for the rare decay K_L -> pi^0 nu nubar in the KTeV experiment at Fermilab. We searched for two-photon events whose kinematics were consistent with an isolated pi^0 coming from the decay K_L -> pi^0 nu nubar. One candidate event was observed, which was consistent with the expected level of background. An upper limit on the branching ratio was determined to be B(K_L -> pi^0 nu nubar) < 1.6E-6 at the 90% confidence level.

We have carried out at Fermilab the first search for the lepton-family number violating decay K L → π 0 μ ± e ∓ . There were no events observed. By normalizing to K L → π + π − π 0 decays collected simultaneously, the 90% confidence level upper limit on 1 2 [ BR (K L →π 0 μ + e − )+ BR (K L →π 0 μ − e + )] was determined to be 3.1×10 −9 .

We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R0 hadron, which is the lightest bound state of a gluon and a light gluino, and thereby also the possibility of a light gluino. Depending on the photino mass, we exclude the R0 in the mass and lifetime ranges of 1.2 -- 4.6 GeV and 2E-10 -- 7E-4 seconds, respectively. (To Appear in Phys. Rev. Lett.), Documentstyle aps,epsfig,prl (revtex), 6 pages, 7 figures

We present a comprehensive treatment of the precise determinations of the parameters Re({var_epsilon}{sup {prime}}/{var_epsilon}), {tau}{sub S}, {Delta}m, {phi}{sub +{minus}}, and {Delta}{phi} in the neutral kaon system with the Fermilab E731 detector. Together, these determinations allow accurate studies of both CP and CPT symmetry. Details of the detector and its performance and the data analysis are given. The extensive Monte Carlo simulation of the detector and comparison with data are also presented. {copyright} {ital 1997} {ital The American Physical Society}

Fermilab is the nation’s particle physics laboratory, supported by the DOE Office of High Energy Physics (OHEP). Fermilab is a world leader in accelerators, with a demonstrated track-record— spanning four decades—of excellence in accelerator science and technology. We describe the significant opportunity to complete, in a highly leveraged manner, a unique accelerator research facility that supports the broad strategic goals in accelerator science and technology within the OHEP. While the US accelerator-based HEP program is oriented toward the Intensity Frontier, which requires modern superconducting linear accelerators and advanced highintensity storage rings, there are no accelerator test facilities that support the accelerator science of the Intensity Frontier. Further, nearly all proposed future accelerators for Discovery Science will rely on superconducting radiofrequency (SRF) acceleration, yet there are no dedicated test facilities to study SRF capabilities for beam acceleration and manipulation in prototypic conditions. Finally, there are a wide range of experiments and research programs beyond particle physics that require the unique beam parameters that will only be available at Fermilab’s Advanced Superconducting Test Accelerator (ASTA). To address these needs we submit this proposal for an Accelerator R&D User Facility at ASTA. The ASTA program is based on the capability provided by an SRF linac (which provides electron beams from 50 MeV to nearly 1 GeV) and a small storage ring (with the ability to store either electrons or protons) to enable a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop transformative approaches to particle-beam generation, acceleration and manipulation which cannot be done elsewhere. It will also establish a unique resource for R&D towards Energy Frontier facilities and a test-bed for SRF accelerators and high brightness beam applications in support of the OHEP mission of Accelerator Stewardship.

The rst 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 ! e oscillations at the second oscillation maximum. We

We present the first evidence for the decay {ital K}{sub {ital L}}{r_arrow}{ital e}{sup +}{ital e}{sup {minus}}{mu}{sup +}{mu}{sup {minus}} based on the observation of one event with an estimated background of 0.067{sub {minus}0.025}{sup +0.057} event. We determine the branching ratio to be {ital B}({ital K}{sub {ital L}}{r_arrow}{ital e}{sup +}{ital e}{sup {minus}}{mu}{sup +}{mu}{sup {minus}})=(2.9{sub {minus}2.4}{sup +6.7}){times}10{sup {minus}9}. In addition, we set a 90{percent} confidence upper limit on the combined branching ratio for the lepton flavor violating decays {ital K}{sub {ital L}}{r_arrow}{ital e}{sup {minus_plus}}{ital e}{sup {minus_plus}}{mu}{sup {plus_minus}}{mu}{sup {plus_minus}} to be {ital B}({ital K}{sub {ital L}}{r_arrow}{ital e}{sup {minus_plus}}{ital e}{sup {minus_plus}}{mu}{sup {plus_minus}}{mu}{sup {plus_minus}}){lt}6.1{times}10{sup {minus}9} assuming a uniform phase space distribution. {copyright} {ital 1996 The American Physical Society.}

A prototype electromagnetic calorimeter for the KTeV experiment at Fermilab was tested at the CERN X1 beam-line. The calorimeter consisted of undoped cesium iodide crystals which were exposed to electrons, pions and muons. This test also featured a new digital readout system with 17 bits of dynamic range. The electron energy resolution is better than 1% at 5 GeV/c, and less than 0.5% at 60 GeV/c. The rejection factor for 40 GeV/c pions is estimated to be several hundred with 95% electron efficiency.

We have measured the {ital CP} violation parameter {eta}{sub +{minus}{gamma}} in a neutral kaon experiment, E773, at Fermilab. This parameter characterizes {ital CP} violation in the decay {ital K}{sub {ital L}}{r_arrow}{pi}{sup +}{pi}{sup {minus}}{gamma}. Kaon decays into {pi}{sup +}{pi}{sup {minus}} collected simultaneously were used for normalization. Our result is {vert_bar}{eta}{sub +{minus}{gamma}}{vert_bar}=[2.359 {plus_minus} 0.062(stat) {plus_minus} 0.040(syst)] {times} 10{sup {minus}3} with a phase {phi}{sub +{minus}{gamma}} = [43.8 {plus_minus} 3.5(stat) {times} 1.9(syst){degree}]. The prediction that {eta}{sub +{minus}{gamma}} should be very close to {eta}{sub +{minus}} is supported by our result.

We report on a measurement of the decay {ital K}{sub {ital L}}{r_arrow}{mu}{sup +}{mu}{sup {minus}}{gamma} from Fermilab experiment E799. We observe 207 candidate signal events with an estimated background of 10.5{plus_minus}4.0 events and establish {ital B}({ital K}{sub {ital L}}{r_arrow}{mu}{sup +}{mu}{sup {minus}}{gamma})=[3.23{plus_minus}0.23(stat){plus_minus}0.19(syst)]{times}10{sup {minus}7}. This provides the first measurement of the {ital K}{gamma}{gamma}{sup *} form factor in the muonic Dalitz decay mode of the {ital K}{sub {ital L}}.

We have measured the polarization of Λ and Λ hyperons produced by 800 GeV protons on a Be target at a fixed targeting angle of 4.8 mrad. Comparison with previous data at 400 GeV production energy and twice the targeting angle shows no significant energy dependence for the Λ polarization. This is in striking contrast to the energy dependence found for σ+ and Ξ− polarizations. We find no evidence for Λ polarization at 800 GeV.

We report the results of a search for the decay [ital K][sub [ital L]][sup 0][r arrow][pi][sup 0][pi][sup 0][gamma] conducted by the E799 Collaboration at Fermilab. The amplitude for this process vanishes to [ital O]([ital p][sup 4]) in chiral perturbation theory, so a measurement of the decay would directly probe [ital O]([ital p][sup 6]) effects. This is the first published search for this decay mode and we set a 90% confidence level upper limit on the branching ratio of [ital B]([ital K][sub [ital L]][sup 0][r arrow][pi][sup 0][pi][sup 0][gamma])[lt]2.3[times]10[sup [minus]4].

We have determined the branching ratio of [ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][ital e][sup +][ital e][sup [minus]] based on the observation of 27 four-electron final state events with 0.36 estimated background event, [ital B]([ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][ital e][sup +][ital e][sup [minus]]) =[3.96[plus minus]0.78(stat)[plus minus]0.32(syst)][times]10[sup [minus]8]. Using the distribution of the angle between the [ital e][sup +][ital e][sup [minus]] pair decay planes, we find that the decay proceeds predominantly through the [ital K][sub 2]([ital CP]=[minus]1) state.

A FNAL E799 Collaboration has carried out a search for the lepton-family number violating decay π0 → μ±e∓ using π0's produced from KL → π0π0π0 decays in flight. No events were observed. Assuming that lepton-family number violation is charge independent, the 90% confidence level upper limit on 1 2 [ BR (π 0 → μ + e − ) + BR (π 0 → μ − e + )] was determined to be 8.6 × 10−9.

The KTeV E799 experiment has conducted a search for the rare decays, ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{X}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, where the ${X}^{0}$ is a possible new neutral boson that was reported by the HyperCP experiment with a mass of $(214.3\ifmmode\pm\else\textpm\fi{}0.5)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$. We find no evidence for either decay. We obtain upper limits of $\mathrm{Br}({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{X}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ and $\mathrm{Br}({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l9.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ at the 90% confidence level. This result rules out the pseudoscalar ${X}^{0}$ as an explanation of the HyperCP result under the scenario that the $\overline{d}s{X}^{0}$ coupling is completely real.

The authors present precision measurements of the direct CP violation parameter, Re({epsilon}{prime}/{epsilon}), the kaon parameters, {Delta}m and {tau}{sub S}, and the CPT tests, {phi}{sub {+-}} and {Delta}{phi}, in neutral kaon decays. These results are based on the full dataset collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains {approx} 15 million K {yields} {pi}{sup 0}{pi}{sup 0} decays and {approx} 69 million K {yields} {pi}{sup +}{pi}{sup -} decays. They describe significant improvements to the precision of these measurements relative to previous KTeV analyses. They find Re({epsilon}{prime}/{epsilon}) = [19.2 {+-} 1.1(stat) {+-} 1.8(syst)] x 10{sup -4}, {Delta}m = (5265 {+-} 10) x 10{sup 6} hs{sup -1}, and {tau}{sub S} = (89.62 {+-} 0.05) x 10{sup -12} s. They measure {phi}{sub {+-}} = (44.09 {+-} 1.00){sup o} and {Delta}{phi} = (0.29 {+-} 0.31){sup o}; these results are consistent with CPT symmetry.

We report the results of a search for the decay [ital K][sub [ital L]][r arrow][pi][sup 0][ital e+][ital e[minus]] conducted by E799 at Fermilab. The largest contribution to this decay mode is expected to be [ital CP] violating. Observations of this decay could either confirm the standard model mechanisms for [ital CP] violation or point to physics beyond the standard model. No such events were seen in our search. The 90% confidence level upper limit is determined to be [ital B]([ital K][sub [ital L]][r arrow][pi][sup 0][ital e+][ital e[minus]])[lt]4.3[times]10[sup [minus]9].

We report the results of a search for the decay [ital K][sub [ital L]][r arrow][pi][sup 0][mu][sup +][mu][sup [minus]] conducted by E799 at Fermilab. This decay mode is expected to have significant [ital CP][minus]violating contributions and a direct measurement could either confirm the standard model mechanisms for [ital CP]-violation or point to physics beyond the standard model. No such events were seen. The 90% confidence level upper limit is determined to be [ital B]([ital K][sub [ital L]][r arrow][pi][sup 0][mu][sup +][mu][sup [minus]])[lt]5.1[times]10[sup [minus]9].

The Fermilab E799 Collaboration has carried out a search for the rare decay ${\mathrm{\ensuremath{\pi}}}^{0}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ using ${\mathrm{\ensuremath{\pi}}}^{0}$'s produced from ${\mathit{K}}_{\mathit{L}}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$ decays in flight. We observe a signal of nine events with an ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ mass close to the ${\mathrm{\ensuremath{\pi}}}^{0}$ mass where only one event is predicted from other known processes. From this, we measure B(${\mathrm{\ensuremath{\pi}}}^{0}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$,(${\mathit{m}}_{\mathit{e}\mathit{e}}$/${\mathit{m}}_{\mathrm{\ensuremath{\pi}}}^{0}$${)}^{2}$\ensuremath{\gtrsim}0.95) =[7.${6}_{\mathrm{\ensuremath{-}}2.8}^{+3.9}$(stat)\ifmmode\pm\else\textpm\fi{}0.5(syst)]\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}8}$, over and above the contribution from ${\mathrm{\ensuremath{\pi}}}^{0}$ Dalitz decays. Correcting for radiative effects, we find this result consistent with theoretical expectations from standard-model processes.

A new facility is being planned at Fermilab for fixed target experiments dealing with CP violation in rate neutral kaon decays; and precision measurements on the “direct” CP-violation parameters e′/e in the 2 pi decay mode of the neutral kaon system. This new Kaons at the TeVatron(KTeV) beam line is expected to be in operation in 1994. The most important new detector component in the KTeV spectrometer is the precision electromagnetic calorimeter, consisting of bars of Cesium Iodide crystals. The choice has been motivated by its radiation hardness, speed and light output. The size of this detector is 2 meters square and includes over 3200 blocks which are coupled to photomultipliers. We expect a peak anode current pulse of 100 ma from an80 Gev deposit. The pulse shape approximates a signal with a FWHM of 25 nanoseconds, but contains some energy in a long tail that exists for more than 500 nanoseconds. The design for the data acquisition electronics will measure deposited charge in every channel in two 12 bit linear ranges: a low range of 2 MEV per count up to a maximum signal of 82 GEV and a range that will handle signals ten times larger with the same proportion in energy resolution. Since the total required dynamic range of this design is between 15 and 16 bit resolution, the problem of pedestal and pile up is seriously engaged with the configuration of this design.

With the E731 apparatus at Fermilab, we have simultaneously collected 6859 ${\mathit{K}}_{\mathit{L}}$ and ${\mathit{K}}_{\mathit{S}}$ decays into ${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}. Using our sample of over 370 000 ${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ decays for normalization we have determined that the ratio \ensuremath{\Gamma}(${\mathit{K}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma})/\ensuremath{\Gamma}(${\mathit{K}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$) is (23.0\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ for ${\mathit{K}}_{\mathit{L}}$ and (7.10\ifmmode\pm\else\textpm\fi{}0.22)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ for ${\mathit{K}}_{\mathit{S}}$, for photon energies greater than 20 MeV in the kaon center of mass. After removing the inner-bremsstrahlung contribution, we find that the photon energy spectrum of the direct emission decay of the ${\mathit{K}}_{\mathit{L}}$ is consistent with the presence of a vector meson propagator in the form factor.

Interference between ${\mathrm{K}}_{\mathrm{S}}$ and ${\mathrm{K}}_{\mathrm{L}}$ decays into the final state ${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma} has been observed in experiment 731 at Fermilab. By fitting the distribution of decays downstream of a regenerator, a new CP-violation parameter${\mathrm{\ensuremath{\eta}}}_{+\mathrm{\ensuremath{-}}\ensuremath{\gamma}}$, analogous to ${\mathrm{\ensuremath{\eta}}}_{+\mathrm{\ensuremath{-}}}$, has been measured, with its magnitude equal to(2.15\ifmmode\pm\else\textpm\fi{}0.26\ifmmode\pm\else\textpm\fi{}0.20)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$, and ${\mathrm{\ensuremath{\varphi}}}_{+\mathrm{\ensuremath{-}}\ensuremath{\gamma}}$, the associated phase angle, equal to(72\ifmmode\pm\else\textpm\fi{}23\ifmmode\pm\else\textpm\fi{}17)\ifmmode^\circ\else\textdegree\fi{}. Assuming that any difference between this fit value for ${\mathrm{\ensuremath{\eta}}}_{+\mathrm{\ensuremath{-}}\ensuremath{\gamma}}$ and the previously measured value for${\mathrm{\ensuremath{\eta}}}_{+\mathrm{\ensuremath{-}}}$ can be attributed to direct CP violation in this decay, a limit of|${\mathrm{\ensuremath{\epsilon}}}_{+\mathrm{\ensuremath{-}}\ensuremath{\gamma}}^{\ensuremath{'}}$|/\ensuremath{\epsilon}0.3 at the 90% confidence level has been made. \textcopyright{} 1993 The American Physical Society