MACRO Detector Research Articles

Muon neutrinos with the MACRO detector at L.N.G.S.

The flux of upward-going muons induced by neutrino interactions in the surrounding rock has been measured with the MACRO detector. The zenith angular dependence of the measured flux does not match the expectation in a no-oscillation hypothesis. Results of a search for WIMP particles, for possible emissions from celestial objects and for coincidences of ν-events with γ-ray bursts are given.

Magnetic monopole search with the MACRO detector at Gran Sasso

In this letter we present the results of the search for massive magnetic monopoles in the penetrating cosmic ray radiation using the various subdetectors of the MACRO apparatus, during the period 1989–1995. Flux limits are given for the β = vc range 4 × 10−5 < β < 1; for 10−4 < β < 10−1 the limits are below the Parker bound, ∼ 10−15 cm−2s−1sr−1.

The transition radiation detector of MACRO

The measurement of the residual energy spectrum of secondary muons in the TeV region can offer new experimental opportunities in cosmic ray physics. We present a large area transition radiation detector (TRD) of 36 m 2 active area, partially installed since april 1994 on the underground MACRO detector in order to accomplish such a measurement. First results compared with a Monte Carlo simulation are reported.

High energy cosmic ray physics with the MACRO experiment at Gran Sasso

The multimuon data collected by the MACRO detector at Gran Sasso have been analyzed using a new method. The resulting all-particle spectrum is consistent with EAS measurements but higher and flatter than the one obtained from direct experiments.

Search for magnetic monopoles with the MACRO detector

The MACRO detector has as one of its main goals the search, over a large range of velocities, of superheavy magnetic monopoles well below the astrophysical bounds. It employs three different techniques (limited streamer tubes, liquid scintillators and nuclear track detectors) to gain redundancy and complementarity. A null search from data taken in the period 1989–1995 using single subdetectors will be reported.

Searches for magnetic monopoles with the MACRO detector at Gran Sasso

MACRO is a large area multiple component detector located deep underground in Hall B of the Laboratori Nazionali del Gran Sasso in Italy. Its active components consist of tanks of liquid scintillator and planes of limited streamer tubes. In addition, there are two planar areas covered with passive track-etch plastics. The full detector measures 72 m × 12 m × 9.6 m providing a large sensitive area for the detection of penetrating particles. Multiple electronics systems provide triggering on particles over a wide range of velocities, in particular, for slowly moving massive particles such as grand unified magnetic monopoles. MACRO is sensitive to relativistic particles as well as ones whose velocities are as low as 10 −4 c. Various portions of the MACRO detector have been operational since 1989. Various data sets have been analyzed and although no monopoles have been found, stringent flux limits have been set using a variety of techniques. This paper summarizes the capabilities of MACRO for monopole detection and presents some experimental results which have been obtained to date.

Search for neutrinos from the Sun and the Earth with the MACRO detector

Upward-going muon events collected with the lower half of the MACRO detector have been analyzed in order to search for Weakly Interacting Massive Particles possibly trapped in the core of the Sun and of the Earth. No statistically significant signal could be discriminated over the possible fluctuations of the atmospheric neutrino background. Assuming a particular neutralino model, the explorable neutralino mass region has been considered.

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.

Vertical muon intensity measured with MACRO at the Gran Sasso laboratory.

The vertical underground muon intensity has been measured in the slant depth range 3200--7000 hg cm{sup {minus}2} (standard rock) with the completed lower part of the MACRO detector at the Gran Sasso laboratory, using a large sample of data. These observations are used to compute the surface muon flux and the primary ``all-nucleon`` spectrum. An analysis of systematic uncertainties introduced by the interaction models in the atmosphere and the underground propagation of muons is presented. A comparison of our results with published data is also presented.

Muon astrophysics with the MACRO detector

Muon events collected with the streamer tube system of MACRO have been used to study the vertical muon intensity and to search for astrophysical point sources. New upper limits on the muon fluxes coming from source candidates have been obtained. The μ pair distance distribution and multimuon rates are presented and compared with Monte Carlo predictions for different primary cosmic rays composition models.

Search for slowly moving magnetic monopoles

We report a search for slowly moving magnetic monopoles in the cosmic radiation with the first supermodule of the MACRO detector at Gran Sasso. The absence of candidates established an upper limit on the monopole flux of 5.6 × 10 −15cm −2sr −1s −1 at 90% confidence level for the velocity range of 10 −4 $ ̌ β < 4 × 10 −3 .

Search for slowly moving magnetic monopoles with the MACRO detector.

A search for slowly moving magnetic monopoles in the cosmic radiation was conducted from October 1989 to November 1991 using the large liquid scintillator detector subsystem of the first supermodule of the MACRO detector at the Gran Sasso underground laboratory. The absence of candidates established an upper limit on the monopole flux of 5.6 × 10^(−15) cm^(−2) sr^(−1) s^(−1) at 90% confidence level in the velocity range of 10^(−4)≲β<4×10^(−3). This result places a new constraint on the abundance of monopoles trapped in our solar system.

Muon astronomy with the MACRO detector

We have analyzed a sample of 1.8 x 10 exp 6 muons with E(mu) greater than about 1.3 TeV collected by the first and second supermodules of the MACRO detector at Gran Sasso during the period 1989 February to 1991 February. We have searched for an excess of muons of celestial origin over cosmic-ray background. Our search for steady sources in solid angle bins of 3.0 x 3.0 deg in the declination range -5 to 90 deg was negative; the upper limit with 95 percent C.L. to the muon flux at midlatitudes is less than about 2 x 10 exp -12/sq cm s. In addition, we have searched for muon excesses modulated by the orbital period of selected X-ray sources, including Cyg X-3, Cyg X-1, Her X-1, 4U 0115 + 63, and 4U 1907 + 09. We have no evidence of any bursting activity from Cyg X-3, during our search period, which includes the radio outburst of 1991 January.

Neutrino physics in MACRO at Gran Sasso

The MACRO detector has significant abilities in Neutrino Physics. In this presentation, I concentrate on two areas: the detection of supernova neutrinos and neutrinos from WIMP annihilation in the earth.

First supermodule of the MACRO detector at Gran Sasso

In this paper the design, construction and performance of the lower part of the first supermodule of the MACRO detector is described.

Measurement of the decoherence function with the MACRO detector at Gran Sasso.

A measurement of the underground muon decoherence function has been performed using the multiple muon events collected by the MACRO detector at the Gran Sasso National Laboratory. A detector-independent analysis is presented for different zenith regions and rock depths; this allows direct comparison with any model of hadronic interactions. The measured decoherence function is compared with the predictions of a Monte Carlo simulation based on data taken by recent collider experiments.

Search for neutrino bursts from collapsing stars with the MACRO detector

Search for neutrino bursts from collapsing stars with the MACRO detector

Search for nuclearites using the MACRO detector.

A negative search using 1/12 of the eventual MACRO detector has yielded nuclearite flux limits of 1.1×10−14 cm−2 sr−1 s−1 for 10−10<m<0.1 g, and 5.5×10−15 cm−2 sr−1 s−1 for m>0.1 g. We have modified the formula of De Rújula and Glashow for the light yield of nuclearites to include the uv light absorbed and reemitted in the visible region, and proved that the MACRO sensitivity extends almost to the escape velocity of the Earth. Our flux limit, therefore, can be used to address nuclearites that are possibly trapped in the solar system.Received 8 June 1992DOI:https://doi.org/10.1103/PhysRevLett.69.1860©1992 American Physical Society

Study of the ultrahigh-energy primary-cosmic-ray composition with the MACRO experiment.

We present the analysis of multiple-muon events collected with one supermodule (1013 h live time) and two supermodules (1195 h live time) of the MACRO detector at Gran Sasso, Italy. Multimuon rates are shown to be sensitive to primary-cosmic-ray energies between ∼50 TeV and several thousand TeV. Experimental data are compared with the expected rates from two composition models: a light (i.e., proton-rich) and a heavy (i.e., Fe-rich) composition. The predictions are based on a Monte Carlo simulation of the hadronic interactions of cosmic-ray nuclei, followed by a detailed tracking of the muons through the rock and the experimental apparatus. The results show good sensitivity of the MACRO detector to primary composition. The data exhibit a preference towards the light composition model.Received 26 March 1992DOI:https://doi.org/10.1103/PhysRevD.46.895©1992 American Physical Society

Muon astronomy with the MACRO detector at Gran Sasso

Recent results on muon astronomy from the MACRO experiment at Gran Sasso are presented. An analysis has been performed to search for astrophysical point sources of neutral particles which could produce energetic muons through interactions in the Earth's atmosphere. In this paper, we present results on an all-sky survey for an excess muon flux; searches for steady state and periodic muon signals from several candidate point sources; and a search for a short term variability in the muon flux from the direction of Cygnus X-3.