SENSE: A comparison of photon detection efficiency and optical crosstalk of various SiPM devices

This paper describes a comparison of photon detection efficiency and optical crosstalk measurements performed by three partners: Geneva University, Catania Observatory and Nagoya University. The measurements were compared for three different SiPM devices with different active areas: from 9 $mm^2$ up to 93.6 $mm^2$ produced by Hamamatsu. The objective of this work is to establish the measurements and analysis procedures for calculating the main SiPM parameters and their precision. This work was done in the scope of SENSE project which aims to build roadmap for the last developments in field of sensors for low light level detection

Performance of a small size telescope (SST-1M) camera for gamma-ray astronomy with the Cherenkov Telescope Array

The foreseen implementations of the Small Size Telescopes (SST) in CTA will provide unique insights into the highest energy gamma rays offering fundamental means to discover and under- stand the sources populating the Galaxy and our local neighborhood. Aiming at such a goal, the SST-1M is one of the three different implementations that are being prototyped and tested for CTA. SST-1M is a Davies-Cotton single mirror telescope equipped with a unique camera technology based on SiPMs with demonstrated advantages over classical photomultipliers in terms of duty-cycle. In this contribution, we describe the telescope components, the camera, and the trigger and readout system. The results of the commissioning of the camera using a dedicated test setup are then presented. The performances of the camera first prototype in terms of expected trigger rates and trigger efficiencies for different night-sky background conditions are presented, and the camera response is compared to end-to-end simulations.Comment: All CTA contributions at arXiv:1709.0348

Development of a strategy for calibrating the novel SiPM camera of the SST-1M telescope proposed for the Cherenkov Telescope Array

CTA will comprise a sub-array of up to 70 small size telescopes (SSTs) at the southern array. The SST-1M project, a 4 m-diameter Davies Cotton telescope with 9 degrees FoV and a 1296 pixels SiPM camera, is designed to meet the requirements of the next generation ground based gamma-ray observatory CTA in the energy range above 3 TeV. Silicon photomultipliers (SiPM) cameras of gamma-ray telescopes can achieve good performance even during high night sky background conditions. Defining a fully automated calibration strategy of SiPM cameras is of great importance for large scale production validation and online calibration. The SST-1M sub-consortium developed a software compatible with CTA pipeline software (CTApipe). The calibration of the SST-1M camera is based on the Camera Test Setup (CTS), a set of LED boards mounted in front of the camera. The CTS LEDs are operated in pulsed or continuous mode to emulate signal and night sky background respectively. Continuous and pulsed light data analysis allows us to extract single pixel calibration parameters to be used during CTA operation.Comment: All CTA contributions at arXiv:1709.0348

Control Software for the SST-1M Small-Size Telescope prototype for the Cherenkov Telescope Array

The SST-1M is a 4-m Davies--Cotton atmospheric Cherenkov telescope optimized to provide gamma-ray sensitivity above a few TeV. The SST-1M is proposed as part of the Small-Size Telescope array for the Cherenkov Telescope Array (CTA), the first prototype has already been deployed. The SST-1M control software of all subsystems (active mirror control, drive system, safety system, photo-detection plane, DigiCam, CCD cameras) and the whole telescope itself (master controller) uses the standard software design proposed for all CTA telescopes based on the ALMA Common Software (ACS) developed to control the Atacama Large Millimeter Array (ALMA). Each subsystem is represented by a separate ACS component, which handles the communication to and the operation of the subsystem. Interfacing with the actual hardware is performed via the OPC UA communication protocol, supported either natively by dedicated industrial standard servers (PLCs) or separate service applications developed to wrap lower level protocols (e.g. CAN bus, camera slow control) into OPC UA. Early operations of the telescope without the camera were already carried out. The camera is fully assembled and is capable to perform data acquisition using artificial light source.Comment: In Proceedings of the 35th International Cosmic Ray Conference (ICRC2017), Busan, Korea. All CTA contributions at arXiv:1709.0348

Velocity independent constraints on spin-dependent DM-nucleon interactions from IceCube and PICO

[EN] Adopting the Standard Halo Model (SHM) of an isotropic Maxwellian velocity distribution for dark matter (DM) particles in the Galaxy, the most stringent current constraints on their spin-dependent scattering cross-section with nucleons come from the IceCube neutrino observatory and the PICO-60 C3F8 superheated bubble chamber experiments. The former is sensitive to high energy neutrinos from the self-annihilation of DM particles captured in the Sun, while the latter looks for nuclear recoil events from DM scattering off nucleons. Although slower DM particles are more likely to be captured by the Sun, the faster ones are more likely to be detected by PICO. Recent N-body simulations suggest significant deviations from the SHM for the smooth halo component of the DM, while observations hint at a dominant fraction of the local DM being in substructures. We use the method of Ferrer et al. (JCAP 1509: 052, 2015) to exploit the complementarity between the two approaches and derive conservative constraints on DM-nucleon scattering. Our results constrain sigma SD less than or similar to 3x10-39cm2 (6x10-38cm2) at greater than or similar to 90% C.L. for a DM particle of mass 1 TeV annihilating into tau+tau- (bb) with a local density of rho DM=0.3GeV/cm3. The constraints scale inversely with rho DM and are independent of the DM velocity distribution.Aartsen, MG.; Ackermann, M.; Adams, J.; Aguilar, JA.; Ahlers, M.; Ahrens, M.; Alispach, C.... (2020). Velocity independent constraints on spin-dependent DM-nucleon interactions from IceCube and PICO. The European Physical Journal C. 80(9):1-8. https://doi.org/10.1140/epjc/s10052-020-8069-5S18809F. Ferrer, A. Ibarra, S. Wild, JCAP 1509(09), 052 (2015). arXiv:1506.03386 [hep-ph]S. van den Bergh, Publ. Astron. Soc. Pac. 111, 657 (1999). arXiv:astro-ph/9904251G. Bertone, D. Hooper, J. Silk, Phys. Rept. 405, 279 (2005). arXiv:hep-ph/0404175A.K. Drukier, K. Freese, D.N. Spergel, Phys. Rev. D 33, 3495 (1986)M. Kuhlen, N. Weiner, J. Diemand, P. Madau, B. Moore, D. Potter, J. Stadel, M. Zemp, JCAP 1002, 030 (2010). arXiv:0912.2358 [astro-ph.GA]M. Lisanti, L.E. Strigari, J.G. Wacker, R.H. Wechsler, Phys. Rev. D 83, 023519 (2011). arXiv:1010.4300 [astro-ph.CO]Y.Y. Mao, L.E. Strigari, R.H. Wechsler, H.Y. Wu, O. Hahn, Astrophys. J. 764, 35 (2013). arXiv:1210.2721 [astro-ph.CO]L. Necib, M. Lisanti, V. Belokurov, arXiv:1807.02519 [astro-ph.GA]N.W. Evans, C.A.J. O’Hare, C. McCabe, Phys. Rev. D 99(2), 023012 (2019). arXiv:1810.11468 [astro-ph.GA]M.G. Aartsen et al. [IceCube Collaboration], Eur. Phys. J. C 77, no. 3, 146 (2017) arXiv:1612.05949 [astro-ph.HE]C. Amole et al., [PICO Collaboration]. Phys. Rev. Lett. 118(25), 251301 (2017). arXiv:1702.07666 [astro-ph.CO]M.T. Frandsen, F. Kahlhoefer, C. McCabe, S. Sarkar, K. Schmidt-Hoberg, JCAP 1201, 024 (2012). arXiv:1111.0292 [hep-ph]K. Choi, C. Rott, Y. Itow, JCAP 1405, 049 (2014). arXiv:1312.0273 [astro-ph.HE]A. Achterberg et al., [IceCube Collaboration]. Astropart. Phys. 26, 155 (2006). arXiv:astro-ph/0604450R. Abbasi et al. [IceCube Collaboration], Nucl. Instrum. Meth. A 601, 294 (2009) arXiv:0810.4930 [physics.ins-det]M.G. Aartsen et al. [IceCube Collaboration], JINST 12, no. 03, P03012 (2017) arXiv:1612.05093 [astro-ph.IM]R. Abbasi et al., [IceCube Collaboration]. Astropart. Phys. 35, 615 (2012). arXiv:1109.6096 [astro-ph.IM]G.J. Feldman, R.D. Cousins, Phys. Rev. D 57, 3873 (1998). https://doi.org/10.1103/PhysRevD.57.3873. arXiv:physics/9711021 [physics.data-an]M. Tanabashi et al. [Particle Data Group], Phys. Rev. D 98, no. 3, 030001 (2018)C. Amole et al. [PICO Collaboration], arXiv:1905.12522 [physics.ins-det]C. Amole et al. [PICO Collaboration], Phys. Rev. D 93, no. 5, 052014 (2016) arXiv:1510.07754 [hep-ex]E. Tollerud et al. [ERFA] Computational Science and Discovery, no 8, 1 (2015) https://doi.org/10.5281/zenodo.1021149J.N. Bahcall, R.K. Ulrich, Rev. Mod. Phys. 60, 297 (1988)T. Mumford et al. [SunPy Community] Computational Science and Discovery, no 8, 1 (2015) arXiv:1505.02563 [astro-ph]V. Gluscevic, M.I. Gresham, S.D. McDermott, A.H.G. Peter, K.M. Zurek, JCAP 1512(12), 057 (2015). arXiv:1506.04454 [hep-ph]A.L. Fitzpatrick, W. Haxton, E. Katz, N. Lubbers, Y. Xu, ‘, JCAP 1302, 004 (2013). https://doi.org/10.1088/1475-7516/2013/02/004. arXiv:1203.3542 [hep-ph]A. Ibarra, A. Rappelt, JCAP 1708(08), 039 (2017). arXiv:1703.09168 [hep-ph

Search for neutrino emission from cores of active galactic nuclei

The sources of the majority of the high-energy astrophysical neutrinos observed with the IceCube neutrino telescope at the South Pole are unknown. So far, only a flaring gamma-ray blazar was compellingly associated with the emission of high-energy neutrinos. However, several studies suggest that the neutrino emission from the gamma-ray blazar population only accounts for a small fraction of the total astrophysical neutrino flux. In this work we probe the production of high-energy neutrinos in the cores of active galactic nuclei (AGN), induced by accelerated cosmic rays in the accretion disk region. We present a likelihood analysis based on eight years of IceCube data, searching for a cumulative neutrino signal from three AGN samples created for this work. The neutrino emission is assumed to be proportional to the accretion disk luminosity estimated from the soft x-ray flux. Next to the observed soft x-ray flux, the objects for the three samples have been selected based on their radio emission and infrared color properties. For the largest sample in this search, an excess of high-energy neutrino events with respect to an isotropic background of atmospheric and astrophysical neutrinos is found, corresponding to a post-trial significance of 2.60σ. If interpreted as a genuine signal with the assumptions of a proportionality of x-ray and neutrino fluxes and a model for the subthreshold flux distribution, then this observation implies that at 100 TeV, 27%-100% of the observed neutrinos arise from particle acceleration in the core of AGN at 1σ confidence interval

Search for High-energy Neutrinos from Ultraluminous Infrared Galaxies with IceCube

Ultraluminous infrared galaxies (ULIRGs) have infrared luminosities L IR ≥ 1012 L ⊙, making them the most luminous objects in the infrared sky. These dusty objects are generally powered by starbursts with star formation rates that exceed 100 M ⊙ yr-1, possibly combined with a contribution from an active galactic nucleus. Such environments make ULIRGs plausible sources of astrophysical high-energy neutrinos, which can be observed by the IceCube Neutrino Observatory at the South Pole. We present a stacking search for high-energy neutrinos from a representative sample of 75 ULIRGs with redshift z ≤ 0.13 using 7.5 yr of IceCube data. The results are consistent with a background-only observation, yielding upper limits on the neutrino flux from these 75 ULIRGs. For an unbroken E -2.5 power-law spectrum, we report an upper limit on the stacked flux φνμ+ν¯μ90%=3.24×10-14TeV-1cm-2s-1(E/10TeV)-2.5 at 90% confidence level. In addition, we constrain the contribution of the ULIRG source population to the observed diffuse astrophysical neutrino flux as well as model predictions

Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube data

Many Galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 TeV. For the IceCube Neutrino Observatory located at the South Pole, the southern sky, containing the inner part of the Galactic plane and the Galactic Center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. In this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 TeV from the southern sky. The strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows IceCube searching for point-like sources of neutrinos in the southern sky at energies between 100 GeV and several TeV in the muon neutrino charged current channel. No significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed IceCube detector. Upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere