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M. Spurio

Publications and source records attributed to M. Spurio.

54 records · Page 3Linked to original sources
arXiv2005

Time variations in the deep underground muon flux measured by MACRO

More than 30 million of high-energy muons collected with the MACRO detector at the underground Gran Sasso Laboratory have been used to search for flux variations of different natures. Two kinds of studies were carried out: search for periodic variations and for the occurrence of clusters of events. Different analysis methods, including Lomb-Scargle spectral analysis and Scan Test statistics have been applied to the data.

astro-ph↗
arXiv2005

Search for massive rare particles with the SLIM experiment

The search for magnetic monopoles in the cosmic radiation remains one of the main aims of non-accelerator particle astrophysics. Experiments at high altitude allow lower mass thresholds with respect to detectors at sea level or underground. The SLIM experiment is a large array of nuclear track detectors at the Chacaltaya High Altitude Laboratory (5290 m a.s.l.). The results from the analysis of 171 m$^2$ exposed for more than 3.5 y are here reported. The completion of the analysis of the whole detector will allow to set the lowest flux upper limit for Magnetic Monopoles in the mass range 10$^5$ - 10$^{12}$ GeV. The experiment is also sensitive to SQM nuggets and Q-balls, which are possible Dark Matter candidates.

hep-ex↗
arXiv2005

Search for exotic contributions to atmospheric neutrino oscillations

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant effect. The data disfavor these possibilities even at a sub-dominant level; stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter $|Δv| < 6 \times 10^{-24}$ at $\sin 2θ_v$ = 0 and $|Δv| < 2.5 ÷5 \times 10^{-26}$ at $\sin 2θ_v$ = $\pm$1. The limits can be re-interpreted as bounds on the Equivalence Principle violation parameters.

hep-ex↗
arXiv2005

Search for spontaneous muon emission from lead nuclei

We describe a possible search for muonic radioactivity from lead nuclei using the base elements ("bricks" composed by lead and nuclear emulsion sheets) of the long-baseline OPERA neutrino experiment. We present the results of a Monte Carlo simulation concerning the expected event topologies and estimates of the background events. Using few bricks, we could reach a good sensitivity level.

hep-ex↗
arXiv2005

A parameterisation of single and multiple muons in the deep water or ice

Atmospheric muons play an important role in underwater/ice neutrino detectors. In this paper, a parameterisation of the flux of single and multiple muon events, their lateral distribution and of their energy spectrum is presented. The kinematics parameters were modelled starting from a full Monte Carlo simulation of the interaction of primary cosmic rays with atmospheric nuclei; secondary muons reaching the sea level were propagated in the deep water. The parametric formulas are valid for a vertical depth of 1.5-5 km w.e. and up to 85 deg for the zenith angle, and can be used as input for a fast simulation of atmospheric muons in underwater/ice detectors.

hep-ph↗
arXiv2005

Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data

Neutrino-induced upward-going muons in MACRO have been analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of nu_mu -> nu_tau transitions. The data disfavor these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter |Delta v| < 6 * 10^(-24) at sin2theta_v = 0 and |Delta v| < 2.5--5 * 10^(-26) at sin2theta_v = +/-1. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.

hep-ex↗
arXiv2005

Search for Intermediate Mass Magnetic Monopoles and Nuclearites with the SLIM experiment

SLIM is a large area experiment (440 m2) installed at the Chacaltaya cosmic ray laboratory since 2001, and about 100 m2 at Koksil, Himalaya, since 2003. It is devoted to the search for intermediate mass magnetic monopoles (107-1013 GeV/c2) and nuclearites in the cosmic radiation using stacks of CR39 and Makrofol nuclear track detectors. In four years of operation it will reach a sensitivity to a flux of about 10-15 cm-2 s-1 sr-1. We present the results of the calibration of CR39 and Makrofol and the analysis of a first sample of the exposed detector.

hep-ex↗
arXiv2005

Time correlations of high energy muons in an underground detector

We present the result of a search for correlations in the arrival times of high energy muons collected from 1995 till 2000 with the streamer tube system of the complete MACRO detector at the underground Gran Sasso Lab. Large samples of single muons (8.6 million), double muons (0.46 million) and multiple muons with multiplicities from 3 to 6 (0.08 million) were selected. These samples were used to search for time correlations of cosmic ray particles coming from the whole upper hemisphere or from selected space cones. The results of our analyses confirm with high statistics a random arrival time distribution of high energy cosmic rays.

astro-ph↗
arXiv2002

Fragmentation cross sections of 158 A GeV Pb ions in various targets measured with CR39 nuclear track detectors

We report the measurement of the fragmentation cross sections in high-energy nucleus-nucleus collisions using the 158 A GeV Pb beam from the CERN-SPS. The fragments have charges changed from that of the incident projectile nucleus by $ΔZ=Z_{Pb}-Z_{frag}$, with 8 <ΔZ <75. The targets range from polyethylene to lead. Charge identification is made with CR39 nuclear track detectors, measured with an automatic image analyzer system. The measured fragmentation cross sections are parameterized with an empirical relation in terms of the atomic mass of the target, and of the charge of the final fragment.

hep-ex↗
arXiv2002

Atmospheric neutrino oscillations

The recent results from the Soudan 2, MACRO and SuperKamiokande experiments on atmospheric neutrino oscillations are summarized and discussed. Some features of possible future atmospheric neutrino experiments are presented.

hep-ex↗
arXiv2001

Estimate of the Energy of Upgoing Muons with Multiple Coulomb Scattering

Upward throughgoing muons in underground detectors are induced by atmospheric $ν_μ$ with energies in the $1-10^4 GeV$ range. The oscillations of atmospheric muon neutrinos should affect mainly those with energy smaller than $E_ν\sim 50 GeV$, or $E_μ\le 10 GeV$ . We analyzed the MACRO upward throughgoing muons data set, using the Multiple Coulomb Scattering to estimate the energy $E_μ$ of muons crossing the detector. We analyzed the event distribution for six event subsamples with different values of $<\ell_ν/ E_ν>$. The event distribution is in agreement with the hypothesis of neutrino oscillations with $Δm^2$ few times $10^{-3} eV^2$ and maximum mixing.

hep-ex↗
arXiv2001

MACRO and the atmospheric neutrino problem

After a brief presentation of the MACRO detector we discuss the updated data on atmospheric muon neutrinos, and the interpretation in terms of neutrino oscillations.

hep-ex↗
arXiv2000

Magnetic monopoles, nuclearites, Q-balls: a qualitative picture

We present qualitative pictures of the structures of magnetic monopoles (MMs), nuclearites (nuggets of strange quark matter, strangelets, surrounded by electrons) and Q-balls (supersymmetric states of squarks, sleptons and Higgs fields). In particular we discuss the relation between their mass and size. MMs, nuclearites and Q-balls could be part of the cold Dark Matter (DM); we consider astrophysical limits on the flux of these particles in the cosmic radiation.

hep-ex↗
arXiv2000

Solar panels as air Cherenkov detectors for extremely high energy cosmic rays

Increasing interest towards the observation of the highest energy cosmic rays has motivated the development of new detection techniques. The properties of the Cherenkov photon pulse emitted in the atmosphere by these very rare particles indicate low-cost semiconductor detectors as good candidates for their optical read-out. The aim of this paper is to evaluate the viability of solar panels for this purpose. The experimental framework resulting from measurements performed with suitably-designed solar cells and large conventional photovoltaic areas is presented. A discussion on the obtained and achievable sensitivities follows.

hep-ex↗
arXiv1999

Atmospheric Neutrino Physics with the MACRO detector

We present the measurement of the the flux and angular distribution of atmospheric muon neutrinos using the MACRO detector. Three different event topologies are detected in two different energy ranges. High energy neutrinos (E~80 GeV) via the identification of upward throughgoing muons. Lower energy neutrinos (E~ 4 GeV) via the upgoing stopping and partially contained downgoing muons (ID+UGS), or via the partially contained upgoing muons (IU). The measured flux is reduced with respect to the predictions. For the high energy sample, globally the flux reduction is $0.74\pm 0.054_{stat+sys} \pm 0.12_{th}$ and varies with the zenith angle. The ratio of measured to expected events is almost constant with the zenith angle for the low energy events, and is $0.57 \pm 0.08_{stat+sys} \pm 0.14_{theor}$ for the IU sample, and $0.71 \pm 0.09_{stat+sys} \pm 0.17_{theor}$ for the (ID+UGS). All the data sets are consistent within a scenario of neutrino oscillations, with maximum mixing and $Δm^2 \sim 10^{-3}÷10^{-2} eV^2$.

hep-ex↗
arXiv1999

Atmospheric Neutrinos and Neutrino Oscillations

After some generalities on neutrino oscillations and on neutrinos, the recent experimental results presented by Soudan 2, MACRO and SuperKamiokande at the Neutrino'98 conference are summarized and discussed.

hep-ph↗
arXiv1998

Low energy atmospheric muon neutrinos in MACRO

The flux of low energy neutrinos ( ~ 4 GeV) has been studied with the MACRO detector at Gran Sasso via the detection of muon neutrinos interactions inside the apparatus, and of upward-going stopping muons. Data collected in ~3 y with the full apparatus were analyzed. The results are compatible with a deficit of the flux of atmospheric muon neutrinos from below, and no reduction from above, with respect to Monte Carlo predictions. The deficit and the angular distributions are interpreted in terms of neutrino oscillations, and compared with the MACRO results on the upward throughgoing muons ( ~ 100 GeV).

hep-ex↗