arXiv subjects

Y. Minenkov

Publications and source records attributed to Y. Minenkov.

At least 19 recordsLinked to original sources

arXiv2016

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↗

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↗

arXiv2013

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↗

arXiv2012

Scientific Potential of Einstein Telescope

Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.

gr-qc↗

arXiv2010

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

gr-qc↗

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↗

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↗

arXiv2007

Sensitivity of the spherical gravitational wave detector MiniGRAIL operating at 5 K

We present the performances and the strain sensitivity of the first spherical gravitational wave detector equipped with a capacitive transducer and read out by a low noise two-stage SQUID amplifier and operated at a temperature of 5 K. We characterized the detector performance in terms of thermal and electrical noise in the system output sygnal. We measured a peak strain sensitivity of $1.5\cdot 10^{-20} Hz^{-1/2}$ at 2942.9 Hz. A strain sensitivity of better than $5\cdot 10{-20}Hz{-1/2}$ has been obtained over a bandwidth of 30 Hz. We expect an improvement of more than one order of magnitude when the detector will operate at 50 mK. Our results represent the first step towards the development of an ultracryogenic omnidirectional detector sensitive to gravitational radiation in the 3kHz range.

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↗

arXiv2003

Increasing the bandwidth of resonant gravitational antennas: The case of Explorer

Resonant gravitational wave detectors with an observation bandwidth of tens of hertz are a reality: the antenna Explorer, operated at CERN by the ROG collaboration, has been upgraded with a new read-out. In this new configuration, it exhibits an unprecedented useful bandwidth: in over 55 Hz about its frequency of operation of 919 Hz the spectral sensitivity is better than 10^{-20} /sqrt(Hz) . We describe the detector and its sensitivity and discuss the foreseable upgrades to even larger bandwidths.

gr-qc↗

arXiv2002

Study of the coincidences between the gravitational wave detectors EXPLORER and NAUTILUS in 2001

We report the result from a search for bursts of gravitational waves using data collected by the cryogenic resonant detectors EXPLORER and NAUTILUS during the year 2001, for a total measuring time of 90 days. With these data we repeated the coincidence search performed on the 1998 data (which showed a small coincidence excess) applying data analysis algorithms based on known physical characteristics of the detectors. With the 2001 data a new interesting coincidence excess is found when the detectors are favorably oriented with respect to the Galactic Disk.

gr-qc↗

arXiv2002

Search for correlation between GRB's detected by BeppoSAX and gravitational wave detectors EXPLORER and NAUTILUS

Data obtained during five months of 2001 with the gravitational wave (GW) detectors EXPLORER and NAUTILUS were studied in correlation with the gamma ray burst data (GRB) obtained with the BeppoSAX satellite. During this period BeppoSAX was the only GRB satellite in operation, while EXPLORER and NAUTILUS were the only GW detectors in operation. No correlation between the GW data and the GRB bursts was found. The analysis, performed over 47 GRB's, excludes the presence of signals of amplitude h >=1.2 * 10^{-18}, with 95 % probability, if we allow a time delay between GW bursts and GRB within +-400 s, and h >= 6.5 * 10^{-19}, if the time delay is within +- 5 s. The result is also provided in form of scaled likelihood for unbiased interpretation and easier use for further analysis.

astro-ph↗

arXiv2002

Effect of cosmic rays on the resonant gravitational wave detector NAUTILUS at temperature T=1.5 K

The interaction between cosmic rays and the gravitational wave bar detector NAUTILUS is experimentally studied with the aluminum bar at temperature of T=1.5 K. The results are compared with those obtained in the previous runs when the bar was at T=0.14 K. The results of the run at T = 1.5 K are in agreement with the thermo-acoustic model; no large signals at unexpected rate are noticed, unlike the data taken in the run at T = 0.14 K. The observations suggest a larger efficiency in the mechanism of conversion of the particle energy into vibrational mode energy when the aluminum bar is in the superconductive status.

gr-qc↗

arXiv2000

Study of Coincidences between Resonant Gravitational Wave Detectors

Coincidences are searched with the cryogenic resonant gravitational wave detectors EXPLORER and NAUTILUS, during a period of about six months (2 June-14 December 1998) for a total measuring time of 94.5 days, with the purpose to study new algorithms of analysis, based on the physical characteristics of the detectors.

gr-qc↗

arXiv2000

Energetic Cosmic Rays observed by the resonant gravitational wave detector NAUTILUS

Cosmic ray showers interacting with the resonant mass gravitational wave antenna NAUTILUS have been detected. The experimental results show large signals at a rate much greater than expected. The largest signal corresponds to an energy release in NAUTILUS of 87 TeV. We remark that a resonant mass gravitational wave detector used as particle detector has characteristics different from the usual particle detectors, and it could detect new features of cosmic rays. Among several possibilities, one can invoke unexpected behaviour of superconducting Aluminium as particle detector, producing enhanced signals, the excitation of non-elastic modes with large energy release or anomalies in cosmic rays (for instance, the showers might include exotic particles as nuclearites or Q-balls). Suggestions for explaining these observations are solicited.

gr-qc↗