O. Erriquez

Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment

Neutral kaon pairs produced in phi decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process phi -> KSKL -> pi(+)pi(-)pi(+)pi(-) based on 1.7 fb(-1) of data collected by the KLOE experiment at the Frascati phi-factory DA Phi NE. The data are used to perform a Measurement of the CPT-violating parameters Delta a(mu) for neutral kaons in the context of the Standard Model Extension framework. The parameters measured in the reference frame of the fixed stars are: Delta a(0) = (-6.0 +/- 7.7(stat)+/- 3.1(syst)) X 10(-18) GeV, Delta a(x) = (0.9 +/- 1.5(stat)+/- 0.6(syst)) X 10(-18) GeV, Delta a(y) = (-2.0 +/- 1.5(stat)+/- 0.5(syst)) X 10(-18) GeV, Delta a(z) = (3.1 +/- 1.7(stat)+/- 0.5(syst)) X 10(-18) GeV. These are presently the most precise measurements in the quark sector of the Standard Model Extension

A high rejection transition radiation detector prototype to distinguish positrons from protons in a cosmic ray space laboratory

Abstract We have carefully implemented a transition radiation detector prototype in order to design a similar device having 75 × 150 cm 2 active surface that will discriminate positrons from protons. This detector will be part of the spectrometer of the experiment WIZARD, planned to fly at 180 miles altitude on the NASA Space Station “FREEDOM” to search for primordial antimatter. Since the positron to proton ratio is expected to be of the order of 10 −4 , we have pushed the proton rejection factor of the spectrometer beyond this value using a compact transition radiation detector equipped with properly designed “cluster counting” electronics.

A Study of the Semi-Leptonic Decays of K+ Mesons

Abstract The form factors of the semi-leptonic decays K + → π 0 e + ν and K + → π 0 μ + ν have been investigated using a sample of events detected in the CERN 1.1 m 3 heavy liquid bubble chamber. Analyses have been carried out using methods independent of any assumption of the q 2 dependence of the form factors in addition to the usual linear parametrizations. Consistent results have been obtained from separate studies of both Dalitz plot density distributions and the branching ratio. A parametrized global analysis of both decay modes gives the values ξ (0) = -1.3 ± 0.7 and ξ (4.4 M π 2 ) = -0.45 ± 0.13, or λ 0 = - 0.017 ± 0.011 both for a fitted value of λ + = 0.025 ± 0.007.

Study of the Dalitz decay ϕ → ηe+e− with the KLOE detector

We have studied the vector to pseudoscalar conversion decay phi -> eta e+e-, with eta -> pi0pi0pi0, with the KLOE detector at DAPHNE. The data set of 1.7 fb-1 of e+e- collisions at sqrt(s)~Mphi contains a clear conversion decay signal of ~31,000 events from which we measured a value of BR(phi -> eta e+e-)=(1.075+-0.007+-0.038)x10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining b(phi eta) =(1.17 +- 0.10 + 0.07) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations.

A transition radiation detector for particle astrophysics experiments using low power consumption electronics

Abstract We have designed a transition radiation detector (TRD) of about 75 × 80 cm 2 active surface to discriminate positrons from protons in an experiment to be performed on balloon flights to search for primordial antimatter. The TRD is made of ten modules consisting of a carbon fiber radiator followed by a multiwire proportional chamber (MWPC). In order to achieve a proton-electron rejection factor of the order of 10 −3 with a strict limitation on power consumption to 35 mW per MWPC channel, as required by experimental constraints, we have developed and tested a prototype based on low power consumption “cluster counting” electronics. Comparisons of the performances of this prototype are made with those of a previous similar detector equipped with standard fast electronics and an analogous TRD from other authors.

Transition radiation detectors for underground and space laboratories

Abstract The performances of transition radiation detectors are reviewed. We discuss the applications of these devices to measure the energy of cosmic rays muons in underground laboratories and present the first results from prototypes operating in the TeV energy region. Another interesting application of transition radiation detectors is the discrimination of positron from protons in the outer space to search for primordial antimatter. Prototypes developed for WIZARD experiment are described.

A Muon trigger for the MACRO apparatus

Abstract A trigger circuit based on EPROM components, able to manage up to 30 lines from independent counters, is described. The circuit has been designed and used in the MACRO apparatus at the Gran Sasso Laboratory for triggering on fast particles. The circuit works with standard TTL positive logic and is assembled in a double standard CAMAC module. It has a high triggering capacity and a high flexibility.

MASS-SAT: Matter-Antimatter Space Spectrometer on Satellite

SummaryThe MASS-SAT Experiment (Matter-Antimatter Space Spectrometer on SATellite) presented here is conceived to search for an experimental answer to many open problems related to both Astrophysics and Physics, through the detection of positrons, antiprotons, nuclei and, overall, antinuclei if they exist. Among these problems there are the hypothesized presence of antigalaxies in the Universe (the matter-antimatter symmetry problem), the existence of black holes as possible antiproton sources (the Hawking effect), the existence of photinos as antiproton sources (related to the dark-matter problem), the understanding of the mechanism of cosmic-ray acceleration in the interstellar medium, the determination of the relative abundancies of isotopes in cosmic rays and many others. The choice of an orbit expecially appropriate for that (geostationary or polar orbit) as well as the choice of an apparatus composed only of solid-state detectors and permanent magnets (no gas and no liquid helium on board, avoiding complexity and the necessity of refilling) make it possible to conceive a long (4–5 years) period of data taking with unprecedented sensitivity in the low-energy region of the cosmic-ray spectrum. The MASS-SAT experiment shows itself as the prosecution of the MASS balloon-borne experiment and as the logical complement of the Astromag program on the Space Station Freedom.

Description and performances of a transition radiation detector for a Gran Sasso underground experiment

A transition radiation detector module, 6 × 2 × 2 m3 in size, has been developed, tested and then installed on the MACRO detector at the Gran Sasso National Laboratory. The modular structure consisting of proportional tubes interleaved with polyethylene foam radiators allows to cover a large area. This detector measures the residual energies, up to 1 TeV, of penetrating muons. We discuss the possibility to obtain more physical information from these muons by measuring their residual energy and the performances of the first module. Calibration results of prototypes operated in a test beam at the CERN P.S. are also given.

Status report of the macro experiment at gran sasso

Abstract The half of the MACRO detector, a large area Monopole, Astrophysics, Cosmic Ray Observatory is nearly completed in Hall B of the Gran Sasso Laboratory. One supermodule is already taken data and the remainder will be activated in few months. A general overview of the MACRO detector, together with its physics capabilities as far as the search for point sources of high energy neutrino is concerned, will be presented.