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We report on the search for signatures of possible neutrino radiative decays, in occasion of the 2006 total solar eclipse (TSE). The lower lifetime limits obtained in the hypothesis of normal mass hierarchy (m3 ≫ m2 > m1) are about 3 orders of magnitude better than the previous results. The inverted mass hierarchy scenario (m2 > m1 ≫ m3) is also investigated. The reached sensitivity suggests that the limits presented here are the best obtainable using this technique. [ABSTRACT FROM AUTHOR]

Abstract: The experimental technique of fluorescence light observation is used in current and planned air shower experiments that aim at understanding the origin of ultra-high energy cosmic rays. In the fluorescence technique, the geometry of the shower is reconstructed from the correlation between arrival time and incident angle of the signals detected by the telescope. The calculation of the expected light arrival time used so far in shower reconstruction codes is based on several assumptions. Particularly, it is assumed that fluorescence photons are produced instantaneously during the passage of the shower front and that the fluorescence photons propagate on a straight line with vacuum speed of light towards the telescope. We investigate the validity of these assumptions, how to correct them, and the impact on reconstruction parameters when adopting realistic conditions. Depending on the relative orientation of the shower to the telescope, corrections can reach 100ns in expected light arrival time, 0.1° in arrival direction and 5gcm−2 in depth of shower maximum. The findings are relevant also for the case of “hybrid” observations where the shower is registered simultaneously by fluorescence and surface detectors. [Copyright &y& Elsevier]

We present new data on Cherenkov light observations obtained during 1994-2009 period, after a modernization of the Yakutsk EAS array. A complex analysis of xmax and its fluctuations σ (xmax) was performed in a wide energy range. With the new data, according to QGSJet II model, an estimation was made of cosmic rays mass composition for E0 ~ 1017 - 3 x 1019 eV. The result points towards a mixed composition with a large portion of heavy nuclei at E0 ~ 1017 eV and the dominance of light nuclei at E0 ~ 1019 eV. The analysis of σ (xmax) energy dependence for the same energies qualitatively confirms this result. A shape of xmax distribution at fixed energy 1018 eV is analysed to make more precise conclusion on cosmic ray mass composition. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment is being built at the future Facility for Antiproton and Ion Research (FAIR) next to GSI, Darmstadt, Germany. A RICH detector will provide clean and efficient electron identification in order to access di-electrons emitted from dense baryonic matter, one of the key measurements of CBM. The CBM RICH recently passed the threshold to construction with first mass production of part of the electronics. The readout electronics was developed together with the HADES experiment and is successfully operated there in the upgraded RICH detector which also makes use of approximately half of the H12700 MAPMTs of CBM. The readout electronics is also tested in a dedicated "mini-RICH" detector in the "mini-CBM" setup with prototypes of all subdetectors, however with an implementation of the full functionality of the future free-streaming readout. Besides finalizing the RICH readout, work is ongoing on full size prototypes of the RICH mirror mechanics and the photocamera including a full system test of the cooling concept. In this report, a brief update on the various developments and the status of the CBM RICH detector is given. • CBM RICH passed threshold to construction. • DiRICH based readout chain commonly developed with HADES and validated. • full size photocamera prototype including closed-loop air-cooling. • free-streaming readout developed and validated. [ABSTRACT FROM AUTHOR]

The High Acceptance Dielectron Spectrometer (HADES) situated at GSI Darmstadt, Germany, has recently upgraded its gaseous ring imaging Cherenkov (RICH) detector. Studying the properties of the hot and dense fireballs produced in heavy ion collisions the RICH is the key component to efficiently identify electrons and positrons emitted therein. The new photon detection plane is comprised of 428 multianode photo electron multipliers (MAPMT)(Hamamatsu H12700) partly coated with p-Terphenyl as a wavelength shifter. It is operated with a gaseous C 4 H 10 (isobutane) radiator making it essentially hadron blind for particle momenta up to approximately 2.5 GeV/c. All 27392 MAPMT channels are read out by an FPGA based readout electronic scheme called DIRICH, which will also be used in other future Cherenkov detectors. The DIRICH readout allows to measure leading and trailing edges for each pixel pulse and hence time over threshold and hit arrival time down to sub-nanosecond precision. This article will discuss the key features of the upgraded HADES RICH and its performance based on a Ag+Ag run at E = 1. 58 A GeV incident energy within the FAIR Phase-0 research program. • HADES RICH upgraded with 428 Hamamatsu H12700 MAPMTs. • 200 ps timing precision reachable using DIRICH readout chain for MAPMT readout. • More than 17 hits per ring reached on average over full detector. • Detector integrated average of less than 15 background hits per event. [ABSTRACT FROM AUTHOR]

The DIRICH front-end board (FEB) is a 32+1 channel FPGA based TDC readout module for Multianode Photomultipliers (MAPMT), and also Multianode MCPs. Due to its low cost and excellent timing precision in single photon measurement applications it will be used in the RICH detector of the Compressed Baryonic Matter (CBM) experiment at the future FAIR facility at GSI Darmstadt, Germany. In the regions of highest photon density at the CBM RICH one expects an average hit rate of ≃ 300 kHz per MAPMT pixel (6 mm × 6 mm) and ∼ 15 % occupancy for minimum bias Au+Au collisions at 35 A GeV at an interaction rate of 10 MHz. In order to validate the high-rate capability of the DIRICH readout, a dedicated lab setup simulating realistic detector signals by employing a pulsed picosecond laser light source in combination with a constant current driven LED was commissioned. In this paper the setup is introduced and first results are discussed. We show that individual readout channels can withstand photon rates up to 2.2 MHz per pixel, limited only by maximum data rate capability and buffer size on the front-end board. Using the same setup, also effects of high photon occupancy on the MAPMTs are investigated, which might cause additional signals due to capacitive cross-talk within the MAPMT or readout chain. Occupancies of up to 55% (simultaneous photon hits on more than half of the MAPMT pixels) are investigated, indicating that in the expected occupancy range of 10 % – 15 % the readout works flawlessly with very low cross-talk. [ABSTRACT FROM AUTHOR]

A 64-channel readout and data-acquisition module is described in detail. It consists of an H12700 multianode photomultiplier tube, four PADIWA preamplifier boards, and a TRB v3 card that perform the functions of a time-to-digital converter and a data concentrator. The software modules that are necessary for operation of the prototype are described. The inter-channel delays are calibrated. The drift of individual delays does not exceed 0.5 ns for the entire measurement time. The spectra of the “time over threshold” (ToT) are investigated. The influence of periodic noise pickups and the need to improve circuit designs are revealed. The timing properties of the wavelength shifter and its effect on the detection efficiency for Cherenkov rings are investigated. The most intense component is characterized by a decay time of 1.1 ns and there are components with characteristic times of 3.8 and 45 ns. The influence of single-electron spectrum features on the detection efficiency for photoelectrons and the probability of false hits are determined. The total time resolution of 131 channels is 1.1 ns (FWHM). The results make it possible to use the investigated system of readout and data acquisition in the CBM experiment. Nevertheless, the elimination of the revealed shortcomings will provide the efficiency margin and improve the reliability of the system during long-term operation. [ABSTRACT FROM AUTHOR]

The CBM-RICH detector is designed to identify electrons with momenta up to 8 GeV/ c and high purity as this is essential for the CBM physics program. The detector consist of a CO 2 -gaseous radiator, a spherical mirror system, and Multi-Anode PhotoMultiplier Tubes (MAPMT) of type H12700 from Hamamatsu as photon detectors. The detector concept was verified through R&D studies and a laterally scaled prototype. The results were summarized in a TDR, in which open issues were defined concerning the readout electronics, the shielding of the magnetic stray field in the MAPMT region, the radiation hardness of the MAPMT sensors, and the mechanical holding structure of the mirror system. In this article an overview is given on the CBM RICH development with focus on those open issues. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment at the future FAIR facility will investigate the QCD phase diagram at high net baryon densities and moderate temperatures in A+A collisions from 2 to 11 A GeV (SIS100). Electron identification in CBM will be performed by a Ring Imaging Cherenkov (RICH) detector and Transition Radiation Detectors (TRD). A real size prototype of the RICH detector was tested together with other CBM groups at the CERN PS/T9 beam line in 2014. For the first time the data format used the FLESnet protocol from CBM delivering free streaming data. The analysis was fully performed within the CBMROOT framework. In this contribution the data analysis and the event reconstruction methods which were used for obtained data are discussed. Rings were reconstructed using an algorithm based on the Hough Transform method and their parameters were derived with high accuracy by circle and ellipse fitting procedures. We present results of the application of the presented algorithms. In particular we compare results with and without Wavelength shifting (WLS) coating. [ABSTRACT FROM AUTHOR]

The HADES RICH detector is designed for efficient electron identification (electron momenta up to few GeV) in relativistic heavy ion collisions, and successfully in operation since 1999 at the SIS18 accelerator facility, GSI, Darmstadt, Germany. It uses a gaseous photon detector with reflective CsI cathode deposited on the MWPC pad plane. The CBM experiment at the future FAIR facility in Darmstadt will install a RICH detector utilizing 1100 Hamamatsu H12700 Multianode Photomultiplier tubes. In a joint effort the HADES RICH photon detector will be replaced by a subset of these MAPMTs together with a new FPGA-TDC based readout chain resulting in a significant improvement of e + e − - pair reconstruction efficiency for near future measurement campaigns. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) will investigate the phase diagram of strongly interacting matter at high net-baryon density and moderate temperature in A+A collisions. One of the key detectors of CBM to explore this physics program is a Ring Imaging CHerenkov (RICH) detector for electron identification. For a high performance of the RICH detector precise mirror alignment is essential. A three-step correction cycle has been developed, which will be discussed: First a qualitative, fast check of the mirror positions, second a quantitative determination of possible misalignments and third a software correction routine, allowing a proper functioning of the RICH under misalignment conditions. [ABSTRACT FROM AUTHOR]

We study the thermodynamics of the quark gluon plasma with lattice simulations in the continuum limit up to 1 GeV temperature where we show that a perturbative description already applies. We calculate the effect of the presence of charm quark in the equation of state and also describe the topological features of quantum chromodynamics. This conference contribution is based on Nature 539 (2016) no. 7627, 69–71 and Phys. Rev. D 92 (11) (2015), 114505. [ABSTRACT FROM AUTHOR]

The CBM RICH detector is an integral component of the future CBM experiment at FAIR, providing efficient electron identification and pion suppression necessary for the measurement of rare dileptonic probes in heavy ion collisions. The RICH design is based on CO 2 gas as radiator, a segmented spherical glass focussing mirror with Al+MgF 2 reflective coating, and Multianode Photomultipliers for efficient Cherenkov photon detection. Hamamatsu H12700 MAPMTs have recently been selected as photon sensors, following an extensive sensor evaluation, including irradiation tests to ensure sufficient radiation hardness of the MAPMTs. A brief overview of the detector design and concept is given, results on the radiation hardness of the photon sensors are shown, and the development of a FPGA-TDC based readout chain is discussed. [ABSTRACT FROM AUTHOR]

A real size prototype of the CBM RICH detector was tested in beam at CERN in November 2014 with new readout electronics. A detailed analysis of the timing characteristics of the readout chain will be presented in this article. Results of the time precision measurements for several subsets of all channels and the stability of the fine time calibration will be discussed. The obtained sub-nanosecond time precision allows also to investigate the effect on timing when using additional wavelength-shifting films on top of the MAPMT windows. [ABSTRACT FROM AUTHOR]

In 2015 1100 Multi-Anode Photo-Multipliers (MAPMTs) of type HAMAMATSU H12700 were ordered to equip the photon detection plane of the CBM-RICH and HADES-RICH detectors. Both experiments aim to study the properties of dense matter produced in heavy ion collisions. To measure the characteristics of all ordered MAPMTs and give feedback to the manufacturer, a test bench was built at the University of Wuppertal. This paper describes the working principle of the test bench and compiles the measurements of the first 400 H12700 MAPMTs delivered. The average characteristics of the H12700 gathered from these measurements are discussed and compared to measurements of the HAMAMATSU H8500. [ABSTRACT FROM AUTHOR]

Photomultiplier tubes, in particular multianode photomultiplier tubes, are often used in current accelerator-based nuclear and particle physics experiments for spatially resolved detection of single photons. With increasing luminosity and harsh radiation background, the radiation hardness of these sensors plays an increasingly important role. In an extensive experimental study we have investigated the effects of neutron irradiation, using a fission neutron source, and energetic 60Co γ -irradiation on commercially available Hamamatsu H12700/H8500 MAPMTs. In addition, individual components were irradiated, such as their glass windows and voltage dividers. Additionally, a p -terphenyl based wavelength shifting coating, which can be applied on the MAPMT window to enhance the photon yield, was also tested for its radiation tolerance. [ABSTRACT FROM AUTHOR]

Wavelength-shifting (WLS) films were applied on UV-extended front windows of multianode photomultiplier tubes (MAPMTs) in order to increase the sensitivity of the MAPMTs at shorter wavelengths. The WLS material contained p-Terphenyl as photoactive component, which absorbs shorter wavelength photons ( < 300 nm ) and re-emits fluorescence photons around 350 nm, i.e., at the maximum of the PMTs׳ sensitivity. The films were applied by means of dip-coating and the film performance was studied with respect to quantum efficiency, film homogeneity, and crosstalk on the MAPMTs. Using WLS-film-covered MAPMTs in a gaseous Ring Imaging Cherenkov detector, the number of detected photoelectrons per ring increased by up to 21% in an in-beam test. [ABSTRACT FROM AUTHOR]

The CBM experiment at the future FAIR facility will explore nuclear matter at high net-baryon densities. One of the key observables is di-leptons as they penetrate the created matter without further strong interactions. A gaseous RICH detector in a standard projective geometry using spherical mirrors is one of two detector elements for the required electron identification. The mirror system consists of about 72 trapezoidal mirror tiles. Any misalignment between the tiles relative to the nominal common spherical surface leads to reduction of the reconstruction efficiency of Cherenkov rings and deterioration of their resolution. To determine tolerances in mirror misalignment extensive simulation and measurement studies were carried out. Pure CO 2 will be used as radiator gas. Gas contamination, mainly moisture and Oxygen, reduces the number of detected photons per ring and worsens the quality of reconstructed Cherenkov rings. Therefore a study was carried out to determine tolerances in radiator gas contamination. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment at the future FAIR facility will investigate the QCD phase diagram at high net-baryon densities and moderate temperatures. One of the key signatures will be di-leptons emitted from the hot and dense phase in heavy-ion collisions. Measuring di-electrons, a high purity of identified electrons is required in order to suppress the background. Electron identification in CBM will be performed by a Ring Imaging Cherenkov (RICH) detector and Transition Radiation Detectors (TRD). In order to access the foreseen rare probes, the detector and the data acquisition have to handle interaction rates up to 10 MHz. Therefore, the development of fast and efficient event reconstruction algorithms is an important and challenging task in CBM. In this contribution event reconstruction and electron identification algorithms in the RICH detector are presented. So far they have been developed on simulated data but could already be tested on real data from a RICH prototype testbeam experiment at the CERN-PS. Efficient and fast ring recognition algorithms in the CBM-RICH are based on the Hough Transform method. Due to optical distortions of the rings, an ellipse fitting algorithm was elaborated to improve the ring radius resolution. An efficient algorithm based on the Artificial Neural Network was implemented for electron identification in RICH. All algorithms were significantly optimized to achieve maximum speed and minimum memory consumption. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment will study the properties of super dense nuclear matter by means of heavy ion collisions at the future FAIR facility. An integral detector component is a large Ring Imaging Cherenkov detector with CO 2 gas radiator, which will mainly serve for electron identification and pion suppression necessary to access rare dileptonic probes like e + e − decays of light vector mesons or J/ Ψ . We describe the design of this future RICH detector and focus on results obtained by building a CBM RICH detector prototype tested at CERN-PS. [ABSTRACT FROM AUTHOR]

This contribution describes the current progress on the composition analysis of data recorded with Carpet EAS detector. The focus of the paper is on the methodological side of analysis. [ABSTRACT FROM AUTHOR]

Abstract: The Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) at Darmstadt will be a dedicated heavy-ion experiment for the investigation of baryonic matter at highest net-baryon densities. A RICH detector with CO2 as radiator gas is being developed for clean and efficient electron identification which will be necessary for the measurement of some of the key observables of the physics program of CBM. The status of the development of this RICH detector and results on R&D activities concerning self-triggered readout electronics for PMTs, studies on the usage of wavelength-shifting films, as well as the evaluation of glass mirrors from industrial providers will be presented. [Copyright &y& Elsevier]

Abstract: The surface detector array of the Pierre Auger Observatory comprises 1600 water Cherenkov detectors distributed over an area of . The Cherenkov light is detected by three 9-in. photo-multiplier tubes from which the signals of the anode and last dynode are digitized by 10bit 40MHz FADCs. An Altera Cyclone FPGA is employed to generate different local triggers and to handle the data transfer to a communication board. After briefly discussing the design of the cards we present an autonomous test-bench, which has been set up in order to test the large number of boards prior to installation in the field. The qualification procedure and the results obtained in the laboratory are presented. Up to three years of operation in the field demonstrate a very good performance and reliability of the Front-End cards. [Copyright &y& Elsevier]

Abstract: On basis of the theorem of a universal shower development stating that a hadronically generated extensive air shower is completely described by the primary energy, the position of the shower maximum and a parameter related to the total muon number, the so-called correlation curve method is developed and applied to KASCADE data. Correlation information of the muon and electron content of showers measured by the KASCADE experiment are used for the reconstruction of energy and mass of primary cosmic rays. Systematic uncertainties of the method and the results are discussed in detail. It is shown that by this method general tendencies in spectrum and composition indeed can be revealed, but the absolute normalization in energy and mass scale requires much more detailed simulations. [Copyright &y& Elsevier]

Abstract: We describe the test system built to perform the acceptance tests of more than 11000 photomultiplier (PMT) tubes employed in the fluorescence detector of the Pierre Auger Observatory. The results obtained on the properties of the PMT are presented and discussed. [Copyright &y& Elsevier]

Abstract: Lateral distributions for electrons and muons in extensive air showers measured with the array of the KASCADE experiment are compared to results of simulations based on the high-energy hadronic interaction models QGSJet and SIBYLL. It is shown, that the muon distributions are well described by both models. Deviations are found for the electromagnetic component, where both models predict a steeper lateral shape than observed in the data. For both models the observed lateral shapes of the electron component indicate a transition from a light to a more heavy composition of the cosmic ray spectrum above the knee. [Copyright &y& Elsevier]

Abstract: A composition analysis of KASCADE air shower data is performed by means of unfolding the two-dimensional frequency spectrum of electron and muon numbers. Aim of the analysis is the determination of energy spectra for elemental groups representing the chemical composition of primary cosmic rays. Since such an analysis depends crucially on simulations of air showers the two different hadronic interaction models QGSJet and SIBYLL are used for their generation. The resulting primary energy spectra show that the knee in the all particle spectrum is due to a steepening of the spectra of light elements but, also, that neither of the two simulation sets is able to describe the measured data consistently over the whole energy range with discrepancies appearing in different energy regions. [Copyright &y& Elsevier]

The observation of a small change in spectral slope, or ‘knee’ in the fluxes of cosmic rays near energies 1015 eV has caused much speculation since its discovery over 40 years ago. The origin of this feature remains unknown. A small workshop to review some modern experimental measurements of this region was held at the Adler Planetarium in Chicago, USA in June 2000. This paper summarizes the results presented at this workshop and the discussion of their interpretation in the context of hadronic models of atmospheric air showers. [Copyright &y& Elsevier]

Electron identification in the Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) will be performed using a gaseous RICH detector. Due to the UV transparency of the CO 2 radiator, a high photon detection efficiency of the PMTs in use at small wavelengths is favourable. The use of wavelength shifting (WLS) films aims at increasing the integral quantum efficiency of the photon sensors. WLS films absorb UV photons and re-emit photons at longer wavelengths where the quantum efficiency of common photocathodes is higher. As photon sensors, multianode PMTs (MAPMTs) with bialkali or superbialkali photocathodes and UV-extended windows are envisaged. We present quantum efficiency measurements with and without WLS coating for different types of MAPMTs as well as results from a beam test at the CERN PS. An increased photon yield was observed when using WLS films. In addition, we discuss the effect of WLS films on the spatial resolution of MAPMTs. [ABSTRACT FROM AUTHOR]

Wavelength-shifting (WLS) films of p-terphenyl have been applied by means of dip-coating on the entrance window of the H12700 multi anode photomultiplier (MAPMT) in order to enhance the UV sensitivity. Using coated and uncoated MAPMTs in a CBM RICH testbox in a proton testbeam at the COSY accelerator, an enhancement of the number of hits per ring of 15%–20% depending on cuts has been observed. Due to new fast readout electronics of the RICH detector for the CBM/ HADES experiments, the time response of p-terphenyl has been measured to show a decay constant of 2.35 ns. This compares well with time-resolved fluorescence measurements of the films. • Sensitivity of H12700 MAPMTs extended to UV wavelengths with p-terphenyl films. • Application to Ring Imaging Cherenkov (RICH) Detectors. • Increase in number of hits per ring due to wavelength-shifting films by 15%–20%. • Fast decay time (2.35 ns) measured with CBM/HADES RICH readout electronics. • Good agreement between CBM/HADES RICH and time-resolved fluorescence measurements. [ABSTRACT FROM AUTHOR]

The upgraded HADES RICH detector, as well as the future CBM RICH detector, will both use the same Hamamatsu H12700 Multianode PMTs read out by the newly developed DiRICH FPGA-TDC readout chain for MAPMTs and MCPs. The upgrade of the HADES RICH photon detector has meanwhile been completed, and we are now looking forward to the upcoming physics run in spring 2019. A brief overview on the status of both detector projects is given and supplemented with the recent test-beam results which confirmed the functionality of the DiRICH development before the start of the mass-production of all DiRICH components needed for the HADES RICH upgrade. [ABSTRACT FROM AUTHOR]

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Anti-proton and Ion Research (FAIR) complex will explore the phase diagram of strongly interacting matter at high baryon density and moderate temperatures in A+A collisions. The energy spectrum will start at 2 AGeV/c and extend up to 11 AGeV/c for the heaviest nuclei at the SIS 100 accelerator set-up. To explore the physics program of CBM, a RICH detector will be employed for electron identification and pion suppression in a momentum range up to 8 GeV/c. Mirror alignment is a key issue for a proper detector operation. The final conceptual design for a monitoring system of the alignment of the mirrors of the CBM RICH detector will be introduced. It consists of a fast qualitative check of the alignment as well as two different methods to derive quantitative numbers for misalignments. A software correction cycle had been developed which, once applied allows to get back to physics performances as in an ideally aligned case. • A hardware-based method used to quantify mirror rotations is presented. • Errors up to 2.75% of the applied rotation are observed for a vertical rotation. • Errors up to 14.25% of the applied rotation are observed for a diagonal rotation. • A correction cycle correcting ring-track distance with misaligned mirrors is shown. • Software improvements in ring-track matching and electron ID efficiencies are seen. [ABSTRACT FROM AUTHOR]