Search arXiv⌕ Search

arXiv subjects

F. Ronga

Publications and source records attributed to F. Ronga.

At least 19 recordsLinked to original sources
arXiv2016

Seasonal variations of the rate of multiple-muons in the Gran Sasso underground laboratory

It is well known that the rate of cosmic ray muons depends on the atmospheric temperature, and that for events with a single muon the peak of the rate is in summer, in underground laboratories in the northern hemisphere. In 2015 the MINOS experiment, in USA, found that, for small distances between the multiple-muons, the rate of multiple-muons peaks in the winter and that the amplitude of the modulation is smaller than in the case of a single muon. I have done a re-analysis of data of the past MACRO experiment. The result is that under Gran Sasso the rate of multiple-muons at small distances peaks in the summer. This difference with MINOS could be explained by differences in the atmospheric temperature due to latitude. This results could be of interest for dark matter experiments looking to dark matter seasonal modulation due to the Earth's motion.

physics.ins-det↗
arXiv2015

Dark Matter searches using gravitational wave bar detectors: quark nuggets and newtorites

Many experiments have searched for supersymmetric WIMP dark matter, with null results. This may suggest to look for more exotic possibilities, for example compact ultra-dense quark nuggets, widely discussed in literature with several different names. Nuclearites are an example of candidate compact objects with atomic size cross section. After a short discussion on nuclearites, the result of a nuclearite search with the gravitational wave bar detectors Nautilus and Explorer is reported. The geometrical acceptance of the bar detectors is 19.5 $\rm m^2$ sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. The experimental limits we obtain are of interest because, for nuclearites of mass less than $10^{-5}$ g, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates. Particles with gravitational only interactions (newtorites) are another example. In this case the sensitivity is quite poor and a short discussion is reported on possible improvements.

physics.ins-det↗
arXiv2015

Newtorites in bar detectors of gravitational wave

The detection of particles with only gravitational interactions (Newtorites) in gravitational bar detectors was studied in 1984 by Bernard, De Rujula and Lautrup. The negative results of dark matter searches suggest to look to exotic possibilities like Newtorites. The limits obtained with the Nautilus bar detector will be presented and the possible improvements will be discussed. Since the gravitational coupling is very weak, the possible limits are very far from what is needed for dark matter, but for large masses are the best limits obtained on the Earth. An update of limits for MACRO particles will be given.

physics.ins-det↗
arXiv2013

Quark nuggets search using 2350 Kg gravitational waves aluminum bar detectors

The gravitational wave resonant detectors can be used as detectors of quark nuggets, like nuclearites (nuclear matter with a strange quark). This search has been carried out using data from two 2350 Kg, 2 K cooled, aluminum bar detectors: NAUTILUS, located in Frascati (Italy), and EXPLORER, that was located in CERN Geneva (CH). Both antennas are equipped with cosmic ray shower detectors: signals in the bar due to showers are continuously detected and used to characterize the antenna performances. The bar excitation mechanism is based on the so called thermo-acoustic effect, studied on dedicated experiments that use particle beams. This mechanism predicts that vibrations of bars are induced by the heat deposited in the bar from the particle. The geometrical acceptance of the bar detectors is 19.5 $\rm m^2$ sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. We will show the results of ten years of data from NAUTILUS (2003-2012) and 7 years from EXPLORER (2003-2009). The experimental limits we obtain are of interest because, for nuclearites of mass less than $10^{-4}$ grams, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates.

astro-ph.HE↗
arXiv2012

Analysis of 3 years of data from the gravitational wave detectors EXPLORER and NAUTILUS

We performed a search for short gravitational wave bursts using about 3 years of data of the resonant bar detectors Nautilus and Explorer. Two types of analysis were performed: a search for coincidences with a low background of accidentals (0.1 over the entire period), and the calculation of upper limits on the rate of gravitational wave bursts. Here we give a detailed account of the methodology and we report the results: a null search for coincident events and an upper limit that improves over all previous limits from resonant antennas, and is competitive, in the range h_rss ~1E-19, with limits from interferometric detectors. Some new methodological features are introduced that have proven successful in the upper limits evaluation.

gr-qc↗
arXiv2011

Comparison of muon and neutrino times from decays of mesons in the atmosphere

We propose a test to compare the speed of muons and muon neutrinos produced in the same bundles in the atmosphere. By comparing the arrival times of primary muons and muons induced by neutrinos, experiments such as Super-Kamiokande, IceCube and ANTARES could verify recent hints on the possibility that neutrinos have a velocity larger than the speed of light. For smaller detectors such as MINOS and OPERA, where it may be challenging to recognize downgoing muons induced by neutrinos inside the active volume, another measurement may be possible thanks to the ns-time resolution. The arrival times of muons in a bundle produced by one cosmic ray interaction in the atmosphere should return a value compatible with the time resolution, while if neutrinos have larger velocity than muons some of the muons may arrive slightly earlier in a bundle of particles than others.

hep-ex↗
arXiv2011

Vibrational excitation induced by electron beam and cosmic rays in normal and superconductive aluminum bars

We report new measurements of the acoustic excitation of an Al5056 superconductive bar when hit by an electron beam, in a previously unexplored temperature range, down to 0.35 K. These data, analyzed together with previous results of the RAP experiment obtained for T > 0.54 K, show a vibrational response enhanced by a factor 4.9 with respect to that measured in the normal state. This enhancement explains the anomalous large signals due to cosmic rays previously detected in the NAUTILUS gravitational wave detector.

gr-qc↗
arXiv2011

Implications of Initial LHC Searches for Supersymmetry

The CMS and ATLAS Collaborations have recently published the results of initial direct LHC searches for supersymmetry analyzing ~ 35/pb of data taken at 7 TeV in the centre of mass. We incorporate these results into a frequentist analysis of the probable ranges of parameters of simple versions of the minimal supersymmetric extension of the Standard Model (MSSM), namely the constrained MSSM (CMSSM), a model with common non-universal Higgs masses (NUHM1), the very constrained MSSM (VCMSSM) and minimal supergravity (mSUGRA). We present updated predictions for the gluino mass, m_gl, the light Higgs boson mass, M_h, BR(B_s to mu mu) and the spin-independent dark matter scattering cross section, sigma_SI. The CMS and ATLAS data make inroads into the CMSSM, NUHM1 and VCMSSM (but not mSUGRA) parameter spaces, thereby strengthening previous lower limits on sparticle masses and upper limits on sigma_SI in the CMSSM and VCMSSM. The favoured ranges of BR(B_s to mu mu) in the CMSSM, VCMSSM and mSUGRA are close to the Standard Model, but considerably larger values of BR(B_s to mu mu) are possible in the NUHM1. Applying the CMS and ATLAS constraints improves the consistency of the model predictions for M_h with the LEP exclusion limits.

hep-ph↗
arXiv2010

IGEC2: A 17-month search for gravitational wave bursts in 2005-2007

We present here the results of a 515 days long run of the IGEC2 observatory, consisting of the four resonant mass detectors ALLEGRO, AURIGA, EXPLORER and NAUTILUS. The reported results are related to the fourfold observation time from Nov. 6 2005 until Apr. 14 2007, when Allegro ceased its operation. This period overlapped with the first long term observations performed by the LIGO interferometric detectors. The IGEC observations aim at the identification of gravitational wave candidates with high confidence, keeping the false alarm rate at the level of 1 per century, and high duty cycle, namely 57% with all four sites and 94% with at least three sites in simultaneous observation. The network data analysis is based on time coincidence searches over at least three detectors: the four 3-fold searches and the 4-fold one are combined in a logical OR. We exchanged data with the usual blind procedure, by applying a unique confidential time offset to the events in each set of data. The accidental background was investigated by performing sets of 10^8 coincidence analyses per each detector configuration on off-source data, obtained by shifting the time series of each detector. The thresholds of the five searches were tuned so as to control the overall false alarm rate to 1/century. When the confidential time shifts was disclosed, no gravitational wave candidate was found in the on-source data. As an additional output of this search, we make available to other observatories the list of triple coincidence found below search thresholds, corresponding to a false alarm rate of 1/month.

gr-qc↗
arXiv2009

Experimental study of high energy electron interactions in a superconducting aluminum alloy resonant bar

Peak amplitude measurements of the fundamental mode of oscillation of a suspended aluminum alloy bar hit by an electron beam show that the amplitude is enhanced by a factor ~3.5 when the material is in the superconducting state. This result is consistent with the cosmic ray observations made by the resonant gravitational wave detector NAUTILUS, made of the same alloy, when operated in the superconducting state. A comparison of the experimental data with the predictions of the model describing the underlying physical process is also presented.

gr-qc↗
arXiv2008

Proceedings of SuperB Workshop VI: New Physics at the Super Flavor Factory

The sixth SuperB Workshop was convened in response to questions posed by the INFN Review Committee, evaluating the SuperB project at the request of INFN. The working groups addressed the capability of a high-luminosity flavor factory that can gather a data sample of 50 to 75 /ab in five years to elucidate New Physics phenomena unearthed at the LHC. This report summarizes the results of the Workshop.

hep-ph↗
arXiv2008

All-sky search of NAUTILUS data

A search for periodic gravitational-wave signals from isolated neutron stars in the NAUTILUS detector data is presented. We have analyzed half a year of data over the frequency band $<922.2; 923.2>$ Hz, the spindown range $<-1.463\times10^{-8}; 0>$ Hz/s and over the entire sky. We have divided the data into 2 day stretches and we have analyzed each stretch coherently using matched filtering. We have imposed a low threshold for the optimal detection statistic to obtain a set of candidates that are further examined for coincidences among various data stretches. For some candidates we have also investigated the change of the signal-to-noise ratio when we increase the observation time from two to four days. Our analysis has not revealed any gravitational-wave signals. Therefore we have imposed upper limits on the dimensionless gravitational-wave amplitude over the parameter space that we have searched. Depending on frequency, our upper limit ranges from $3.4 \times 10^{-23}$ to $1.3 \times 10^{-22}$. We have attempted a statistical verification of the hypotheses leading to our conclusions. We estimate that our upper limit is accurate to within 18%.

gr-qc↗
arXiv2008

Detection of high energy cosmic rays with the resonant gravitational wave detector NAUTILUS and EXPLORER

The cryogenic resonant gravitational wave detectors NAUTILUS and EXPLORER, made of an aluminum alloy bar, can detect cosmic ray showers. At temperatures above 1 K, when the material is in the normal conducting state, the measured signals are in good agreement with the values expected based on the cosmic rays data and on the thermo-acoustic model. When NAUTILUS was operated at the temperature of 0.14 K, in superconductive state, large signals produced by cosmic ray interactions, more energetic than expected, were recorded. The NAUTILUS data in this case are in agreement with the measurements done by a dedicated experiment on a particle beam. The biggest recorded event was in EXPLORER and excited the first longitudinal mode to a vibrational energy of about 670 K, corresponding to about 360 TeV absorbed in the bar. Cosmic rays can be an important background in future acoustic detectors of improved sensitivity. At present, they represent a useful tool to verify the gravitational wave antenna performance.

hep-ex↗
arXiv2007

All-sky incoherent search for periodic signals with Explorer 2005 data

The data collected during 2005 by the resonant bar Explorer are divided into segments and incoherently summed in order to perform an all-sky search for periodic gravitational wave signals. The parameter space of the search spanned about 40 Hz in frequency, over 23927 positions in the sky. Neither source orbital corrections nor spindown parameters have been included, with the result that the search was sensible to isolated neutron stars with a frequency drift less than 6 X 10^{-11} Hz/s. No gravitational wave candidates have been found by means of the present analysis, which led to a best upper limit of 3.1 X 10^{-23} for the dimensionless strain amplitude.

gr-qc↗
arXiv2005

Particle acoustic detection in gravitational wave aluminum resonant antennas

The results on cosmic rays detected by the gravitational antenna NAUTILUS have motivated an experiment (RAP) based on a suspended cylindrical bar, which is made of the same aluminum alloy as NAUTILUS and is exposed to a high energy electron beam. Mechanical vibrations originate from the local thermal expansion caused by warming up due to the energy lost by particles crossing the material. The aim of the experiment is to measure the amplitude of the fundamental longitudinal vibration at different temperatures. We report on the results obtained down to a temperature of about 4 K, which agree at the level of about 10% with the predictions of the model describing the underlying physical process.

gr-qc↗
arXiv2005

Cumulative analysis of the association between the gravitational wave detectors NAUTILUS and EXPLORER and the gamma-ray bursts detected by BATSE and BeppoSAX

The statistical association between the output of the Gravitational Wave (GW) detectors EXPLORER and NAUTILUS and a list of Gamma Ray Bursts (GRBs) detected by the satellite experiments BATSE and BeppoSAX has been analyzed using cumulative algorithms. GW detector data collected between 1991 and 1999 have been correlated to the GRB flux peak times. The cumulative analysis of a large number of GRBs (387) allows to push the upper bound for the corresponding GW burst amplitude down to $h = 2.5\cdot10^{-19}$.

astro-ph↗
arXiv2003

Comments on the 2001 run of the EXPLORER/NAUTILUS gravitational wave experiment

The recently published analysis of the coincidences between the EXPLORER and NAUTILUS gravitational wave detectors in the year 2001 (Astone et al. 2002) has drawn some criticism (Finn 2003). We do not hold with these objections, even if we agree that no claim can be made with our data. The paper we published reports data of unprecedented quality and sets a new procedure for the coincidence search, which can be repeated again by us and by other groups in order to search for signature of possible signals. About the reported coincidence excess, we remark that it is not destined to remain an intriguing observation for long: it will be confirmed or denied soon by interferometers and bars operating at their expected sensitivity.

gr-qc↗