arXiv subjects

S. Gninenko

Publications and source records attributed to S. Gninenko.

At least 37 records · Page 2Linked to original sources

arXiv2015

New solar axion search in CAST with $^4$He filling

The CERN Axion Solar Telescope (CAST) searches for $a\toγ$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the X-ray refractive mass $m_γ$ to the axion search mass $m_a$. After the vacuum phase (2003--2004), which is optimal for $m_a\lesssim0.02$ eV, we used $^4$He in 2005--2007 to cover the mass range of 0.02--0.39 eV and $^3$He in 2009--2011 to scan from 0.39--1.17 eV. After improving the detectors and shielding, we returned to $^4$He in 2012 to investigate a narrow $m_a$ range around 0.2 eV ("candidate setting" of our earlier search) and 0.39--0.42 eV, the upper axion mass range reachable with $^4$He, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to $g_{aγ}< 1.47\times10^{-10} {\rm GeV}^{-1}$ (95% C.L.), depending on the pressure settings. Since 2013, we have returned to vacuum and aim for a significant increase in sensitivity.

hep-ex↗

arXiv2015

Operation and performance of the ICARUS-T600 cryogenic plant at Gran Sasso underground Laboratory

ICARUS T600 liquid argon time projection chamber is the first large mass electronic detector of a new generation able to combine the imaging capabilities of the old bubble chambers with the excellent calorimetric energy measurement. After the three months demonstration run on surface in Pavia during 2001, the T600 cryogenic plant was significantly revised, in terms of reliability and safety, in view of its long-term operation in an underground environment. The T600 detector was activated in Hall B of the INFN Gran Sasso Laboratory during Spring 2010, where it was operated without interruption for about three years, taking data exposed to the CERN to Gran Sasso long baseline neutrino beam and cosmic rays. In this paper the T600 cryogenic plant is described in detail together with the commissioning procedures that lead to the successful operation of the detector shortly after the end of the filling with liquid Argon. Overall plant performance and stability during the long-term underground operation are discussed. Finally, the decommissioning procedures, carried out about six months after the end of the CNGS neutrino beam operation, are reported.

physics.ins-det↗

arXiv2015

A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam

A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.

physics.ins-det↗

arXiv2015

Some conclusive considerations on the comparison of the ICARUS nu_mu to nu_e oscillation search with the MiniBooNE low-energy event excess

A sensitive search for anomalous LSND-like nu_mu to nu_e oscillations has been performed by the ICARUS Collaboration exposing the T600 LAr-TPC to the CERN to Gran Sasso (CNGS) neutrino beam. The result is compatible with the absence of additional anomalous contributions giving a limit to oscillation probability of 3.4E-3 and 7.6E-3 at 90% and 99% confidence levels respectively showing a tension between these new limits and the low-energy event excess (200 < E_nu QE < 475 MeV) reported by MiniBooNE Collaboration. A more detailed comparison of the ICARUS data with the MiniBooNE low-energy excess has been performed, including the energy resolution as obtained from the official MiniBooNE data release. As a result the previously reported tension is confirmed at 90% C.L., suggesting an unexplained nature or an otherwise instrumental effect for the MiniBooNE low energy event excess

hep-ph↗

arXiv2015

Experimental observation of an extremely high electron lifetime with the ICARUS-T600 LAr-TPC

The ICARUS T600 detector, the largest liquid Argon Time Projection Chamber (LAr-TPC) realized after many years of RD activities, was installed and successfully operated for 3 years at the INFN Gran Sasso underground Laboratory. One of the most important issues was the need of an extremely low residual electronegative impurity content in the liquid Argon, in order to transport the free electrons created by the ionizing particles with a very small attenuation along the drift path. The solutions adopted for the Argon re-circulation and purification systems have permitted to reach impressive results in terms of Argon purity and a free electron lifetime exceeding 15 ms, corresponding to about 20 parts per trillion of equivalent O2 contamination, a milestone for any future project involving LAr-TPC's and the development of higher detector mass scales.

physics.ins-det↗

arXiv2014

CAST solar axion search with 3^He buffer gas: Closing the hot dark matter gap

The CERN Axion Solar Telescope (CAST) has finished its search for solar axions with 3^He buffer gas, covering the search range 0.64 eV < m_a <1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 3.3 x 10^{-10} GeV^{-1} at 95% CL, with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of g_a, for example by the currently discussed next generation helioscope IAXO.

hep-ex↗

arXiv2014

The trigger system of the ICARUS experiment for the CNGS beam

The ICARUS T600 detector, with its 470 tons of active mass, is the largest liquid Argon TPC ever built. Operated for three years in the LNGS underground laboratory, it has collected thousands of CNGS neutrino beam interactions and cosmic ray events with energy spanning from tens of MeV to tens of GeV, with a trigger system based on scintillation light, charge signal on TPC wires and time information (for beam related events only). The performance of trigger system in terms of efficiency, background and live-time as a function of the event energy for the CNGS data taking is presented.

physics.ins-det↗

arXiv2014

Conceptual Design of the International Axion Observatory (IAXO)

The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few $\times 10^{-12}$ GeV$^{-1}$ and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling $g_{ae}$ with sensitivity $-$for the first time$-$ to values of $g_{ae}$ not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x-ray optics, able to focus the signal photons into $\sim 0.2$ cm$^2$ spots that are imaged by ultra-low-background Micromegas x-ray detectors. The magnet is built into a structure with elevation and azimuth drives that will allow for solar tracking for $\sim$12 h each day.

physics.ins-det↗

arXiv2014

ICARUS at FNAL

The INFN and the ICARUS collaboration originally developed the technology of the LAr-TPC. Located the underground LNGS Hall-B, the ICARUS T600 detector has been performed over three years with remarkable detection efficiency featuring a smooth operation, high live time, and high reliability. About 3000 CNGS neutrino events have been collected and are being actively analyzed. ICARUS will now be moved to CERN for an extensive R&D program. The T600 detector will be overhauled and complemented with a similar T150 detector. These improvements are performed in collaboration with the LBNE experiment, of which several INFN Institutions are now members. As a novelty, a SC magnetic field of about 1 T will be introduced. During 2016 it is proposed to move the experiment to FNAL where short base line neutrino beams are available, complementing the approved MicroBooNe experiment which will start operation in 2014. The ICARUS detectors at FNAL will be an important addition since, in absence of anomalies, the signals of several detectors at different distances from the target should be a copy of each other for all experimental signatures. Due to the reduced mass, in MicroBooNE the anti-neutrino signal is too weak for a sensitive comparison. Hence, a definitive clarification of the LSND anomaly requires the exploration of the anti-neutrino signal provided by the much larger T600. The magnetic field will allow separating the anti-neutrino signal from the neutrino-induced background. It is proposed to expose the T600 at the Booster NuBeam at ~700 m from target; the T150 will be located at ~150 m. The T600 will also receive >10^4 nu_e events/year from the off-axis NUMI beam peaked around 1 GeV and exploitable to prepare for the LBNE experiment. The ICARUS teams are also interested in extending the participation to other short baseline neutrino activities collaborating with existing FNAL groups.

physics.ins-det↗

arXiv2013

Search for anomalies in the νe appearance from a νμ beam

We report an updated result from the ICARUS experiment on the search for νμ ->νe anomalies with the CNGS beam, produced at CERN with an average energy of 20 GeV and travelling 730 km to the Gran Sasso Laboratory. The present analysis is based on a total sample of 1995 events of CNGS neutrino interactions, which corresponds to an almost doubled sample with respect to the previously published result. Four clear νe events have been visually identified over the full sample, compared with an expectation of 6.4 +- 0.9 events from conventional sources. The result is compatible with the absence of additional anomalous contributions. At 90% and 99% confidence levels the limits to possible oscillated events are 3.7 and 8.3 respectively. The corresponding limit to oscillation probability becomes consequently 3.4 x 10-3 and 7.6 x 10-3 respectively. The present result confirms, with an improved sensitivity, the early result already published by the ICARUS collaboration.

hep-ex↗

arXiv2013

CAST constraints on the axion-electron coupling

In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces a strong axion flux by bremsstrahlung, Compton scattering, and axio-recombination, the "BCA processes." Based on a new calculation of this flux, including for the first time axio-recombination, we derive limits on the axion-electron Yukawa coupling g_ae and axion-photon interaction strength g_ag using the CAST phase-I data (vacuum phase). For m_a < 10 meV/c2 we find g_ag x g_ae< 8.1 x 10^-23 GeV^-1 at 95% CL. We stress that a next-generation axion helioscope such as the proposed IAXO could push this sensitivity into a range beyond stellar energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission.

astro-ph.SR↗

arXiv2013

Experimental search for the LSND anomaly with the ICARUS detector in the CNGS neutrino beam

We report an early result from the ICARUS experiment on the search for nu_mu to nu_e signal due to the LSND anomaly. The search was performed with the ICARUS T600 detector located at the Gran Sasso Laboratory, receiving CNGS neutrinos from CERN at an average energy of about 20 GeV, after a flight path of about 730 km. The LSND anomaly would manifest as an excess of nu_e events, characterized by a fast energy oscillation averaging approximately to sin^2(1.27 Dm^2_new L/ E_nu) = 1/2. The present analysis is based on 1091 neutrino events, which are about 50% of the ICARUS data collected in 2010-2011. Two clear nu_e events have been found, compared with the expectation of 3.7 +/- 0.6 events from conventional sources. Within the range of our observations, this result is compatible with the absence of a LSND anomaly. At 90% and 99% confidence levels the limits of 3.4 and 7.3 events corresponding to oscillation probabilities of 5.4 10^-3 and 1.1 10^-2 are set respectively. The result strongly limits the window of open options for the LSND anomaly to a narrow region around (Dm^2, sin^2(2 theta))_new = (0.5 eV^2, 0.005), where there is an overall agreement (90% CL) between the present ICARUS limit, the published limits of KARMEN and the published positive signals of LSND and MiniBooNE Collaborations.

hep-ex↗

arXiv2013

IAXO - The International Axion Observatory

The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of a few 10^{-12} GeV^{-1}, i.e. 1-1.5 orders of magnitude beyond sensitivities achieved by the currently most sensitive axion helioscope, the CERN Axion Solar Telescope (CAST). Crucial factors in improving the sensitivity for IAXO are the increase of the magnetic field volume together with the extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested at CAST. Electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) along with other novel excitations at the low-energy frontier of elementary particle physics could provide additional physics motivation for IAXO.

physics.ins-det↗

arXiv2013

Precise 3D track reconstruction algorithm for the ICARUS T600 liquid argon time projection chamber detector

Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to fully exploit the potential of this technology. In this paper we present a new, general approach of three-dimensional reconstruction for the LAr TPC with a practical application to track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of real data tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.

physics.ins-det↗

arXiv2012

Results and perspectives of the solar axion search with the CAST experiment

The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be presented. Recent results obtained by the use of $^3$He as a buffer gas has allowed us to extend our sensitivity to higher axion masses than our previous measurements with $^4$He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV$ \le m_{a} \le $ 0.64 eV. From the absence of an excess of x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g$_{aγ} \le 2.3\times 10^{-10}$ GeV$^{-1}$ at 95% C.L., the exact value depending on the pressure setting. CAST published results represent the best experimental limit on the photon couplings to axions and other similar exotic particles dubbed WISPs (Weakly Interacting Slim Particles) in the considered mass range and for the first time the limit enters the region favored by QCD axion models. Preliminary sensitivities for axion masses up to 1.16 eV will also be shown reaching mean upper limits on the axion-photon coupling of g$_{aγ} \le 3.5\times 10^{-10}$ GeV$^{-1}$ at 95% C.L. Expected sensibilities for the extension of the CAST program up to 2014 will be presented. Moreover long term options for a new helioscope experiment will be evoked.

hep-ex↗

arXiv2012

CAST search for sub-eV mass solar axions with 3He buffer gas

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV < m_a < 0.64 eV. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 2.3 x 10^{-10} GeV^{-1} at 95% CL, the exact value depending on the pressure setting. KSVZ axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In future we will extend our search to m_a < 1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.

hep-ex↗

arXiv2012

Search for anomalies in the neutrino sector with muon spectrometers and large LArTPC imaging detectors at CERN

A new experiment with an intense ~2 GeV neutrino beam at CERN SPS is proposed in order to definitely clarify the possible existence of additional neutrino states, as pointed out by neutrino calibration source experiments, reactor and accelerator experiments and measure the corresponding oscillation parameters. The experiment is based on two identical LAr-TPCs complemented by magnetized spectrometers detecting electron and muon neutrino events at Far and Near positions, 1600 m and 300 m from the proton target, respectively. The ICARUS T600 detector, the largest LAr-TPC ever built with a size of about 600 ton of imaging mass, now running in the LNGS underground laboratory, will be moved at the CERN Far position. An additional 1/4 of the T600 detector (T150) will be constructed and located in the Near position. Two large area spectrometers will be placed downstream of the two LAr-TPC detectors to perform charge identification and muon momentum measurements from sub-GeV to several GeV energy range, greatly complementing the physics capabilities. This experiment will offer remarkable discovery potentialities, collecting a very large number of unbiased events both in the neutrino and antineutrino channels, largely adequate to definitely settle the origin of the observed neutrino-related anomalies.

physics.ins-det↗

arXiv2012

Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam

During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks for a total of 1.8 10^17 pot in bunched mode, with a 3 ns narrow width proton beam bunches, separated by 100 ns. This tightly bunched beam structure allows a very accurate time of flight measurement of neutrinos from CERN to LNGS on an event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing synchronization have been substantially improved for this campaign, taking ad-vantage of additional independent GPS receivers, both at CERN and LNGS as well as of the deployment of the "White Rabbit" protocol both at CERN and LNGS. The ICARUS-T600 detector has collected 25 beam-associated events; the corresponding time of flight has been accurately evaluated, using all different time synchronization paths. The measured neutrino time of flight is compatible with the arrival of all events with speed equivalent to the one of light: the difference between the expected value based on the speed of light and the measured value is tof_c - tof_nu = (0.10 \pm 0.67stat. \pm 2.39syst.) ns. This result is in agreement with the value previously reported by the ICARUS collaboration, tof_c - tof_nu = (0.3 \pm 4.9stat. \pm 9.0syst.) ns, but with improved statistical and systematic errors.

hep-ex↗