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A Modular COsmic Ray Detector (MCORD) was prepared for use in various physics experiments. MCORD detectors can be used in laboratory measurements or can become a part of large measurement sets. MCORD can be used as a muon detector, a veto system, or a tool supporting the testing and calibration of other detectors. MCORD can also work as a stand-alone device for scientific and commercial purposes. The basic element of MCORD is one section consisting of eight oblong scintillators with a double-sided light reading performed by silicon photomultipliers (SiPMs). This work presents a practical description of testing, calibration, and programming of analogue and digital electronics modules. The characterisation and calibration methods of the analogue front-end electronic modules, the obtained results, and their implementation into an operating system are presented. In addition, we describe the development environment and the procedures used to prepare our kit for practical use. The architecture of the FPGAs is also presented with a description of their programming as a data-collecting system in a simple coincidence circuit. We also present the possibilities of extending the data analysis system for large experiments.

In 2009, the King Abdulaziz City for Science and Technology (KACST) launched a project involving the establishment of the first radiation detector laboratory in Saudi Arabia. This project aims to d...

Andes Large-area PArticle detector for Cosmic-ray physics and Astronomy (ALPACA) is an international experiment that applies southern very-high-energy (VHE) gamma-ray astronomy to determine the origin of cosmic rays around the knee energy region ($10^{15}\, {\rm eV} - 10^{16}\, {\rm eV}$). The experiment consists of an air shower (AS) array with a surface of $83, 000\, {\rm m}^2$ and an underground water Cherenkov muon detector (MD) array covering $5, 400\, {\rm m}^2$. The experimental site is at the Mt. Chacaltaya plateau in La Paz, Bolivia, with an altitude of $4, 740\, {\rm m}$ corresponding to $572\, {\rm g}/{\rm cm}^2$ atmospheric thickness. As the prototype experiment of ALPACA, the ALPAQUITA experiment aims to begin data acquisition in late 2021. The ALPAQUITA array consists of a smaller AS array ($18, 450\, {\rm m}^2$) and underground MD ($900\, {\rm m}^2$), which are now under construction. ALPAQUITA's sensitivity to gamma-ray sources is evaluated with Monte Carlo simulations. The simulation finds that five gamma-ray sources observed by H.E.S.S. and HAWC experiments will be detected by ALPAQUITA beyond 10 TeV and one out of these five - HESS J1702-420A - above 300 TeV in one calendar year observation. The latter finding means that scientific discussions can be made on the emission mechanism of gamma rays beyond 100 TeV from southern sources on the basis of the observational results of this prototype experiment., This is the manuscript accepted by Experimental Astronomy. For the published article, see https://doi.org/10.1007/s10686-021-09796-8

In this study, daily cosmic ray data obtained with the KACST muon detector for the period 2002–2012 were analyzed for quasi-periodicities. Power-spectrum analysis was carried out and several periodicities were identified. The results reveal several periodicities at different frequency scales: 817 days (~2.19 years), 617 days (~1.7 years), 475 days (~1.3 years), 421 days (1.15 years), 290 days (~0.8 years), 227 days (~0.62 years), 185 days (~0.52 years), 153 days, 135 days, 120 days, 93 days, 84 days, 73 days, 65 days, 53–45 days, 38 days, 31 days, 25–27 days, 21 days and 13 days. The obtained periodicities are in an agreement with those previously reported by several investigators. The identified periodicities have strong relevance to solar activity parameters such as variations in the interplanetary magnetic field. In comparison, the data from two neutron monitors (NMs), Lomnický stit and Oulu NMs, for the same period were used and their power spectra were correspondingly obtained. Similarities and differences in the position of the cosmic-ray peaks measured by the KACST muon detector and by the two NMs have been presented and discussed. While most of the periodicities reported by the muon detector are also found in the NM data, the ~1.7-yr variation is not found. Instead, a shift of 1.6–1.8 years in the NM data is observed which may be due to the limited epoch considered in this study.

Large-size Resistive Micromegas have been chosen for the upgrade of the forward muon spectrometer of the ATLAS experiment, the New Small Wheel project. These chambers, together with small-strip Thin Gap Chambers (sTGC), allow reconstruction of high-momentum muon tracks in a high-radiation environment and provide a robust low-threshold single-muon trigger. A collaboration of seven INFN units built 32 SM1 type chambers, corresponding to one fourth of the total number needed for this upgrade. Each SM1 chamber has a surface of approximately 2 m2 and four sensitive layers. The production was shared among five INFN construction sites and it was completed in fall 2020. The construction methods, as well as the results of the quality tests done on components of the detector and on the assembled chambers, are reported in the present paper.

In the effort to communicate modern physics to a vast audience, the flux of cosmic ray muons is commonly mentioned as the most abundant, naturally available particle/radioactivity source. The detection of atmospheric muons can therefore make up a powerful workbench for educational purposes, allowing many laboratory experiences in different topics of modern physics like: special relativity, cosmic rays, statistics and particle detection. Unfortunately, a particle detector being suitable for cosmic ray muon identification is typically expensive, cumbersome and requires high voltage, thus preventing its widespread application in laboratory sessions based on cosmic ray muons, ex.gr. for undergraduate courses. Here we describe the project for a low-cost muon detector based on a plastic scintillator coupled with silicon photomultipliers, whose signals are acquired and preprocessed via a common FPGA evaluation board. Besides the detector, which was developed by supervised master students, we describe some possible physics measurements.

The Tibet ASgamma experiment is located at 4,300m above sea level, in Tibet, China.The experiment is composed of a 65,700 m2 surface air shower array and 3,400 m2 underground water Cherenkov muon detectors. The surface air shower array is used for reconstructing the primary particle energy and direction, while the underground muon detectors are used for discriminating gamma-ray induced muon-poor air showers from cosmic-ray (proton, helium,...) induced muon-rich air showers.Recently,the Tibet ASgamma experiment successfully observed gamma rays in the 100 TeV region from some point/extended sources as well as sub-PeV diffuse gamma rays along the Galactic disk.In this talk, The observational results as well as their interpretations will be presented, followed by some future prospect.

The project is conducting a series of muonic X-ray measurements in medium- and high-Z nuclei at PSI, utilizing a high-purity germanium detector array, in-beam muon detectors, and a modern digital data-acquisition system. A novel hydrogen target for muon transfer was developed, enabling measurements with as little as a few micrograms of target material. First measurements with radioactive Cm and Ra targets were conducted, aimed at determining their nuclear charge radii. These serve as important input for upcoming atomic parity violation experiments. The apparatus is also used to perform a feasibility study of an atomic parity violation experiment with the 2s-1s2s−1s muonic X-ray transition. In addition, the setup has been made available for a wider range of nuclear, particle, and solid-state physics measurements.

We report on the observation of an excess of E>300 TeV gamma-ray candidate events in temporal and spatial coincidence with the IceCube high-energy neutrino alert consistent with the origin in the Cygnus Cocoon. The Cygnus Cocoon is a prospective Galactic source of high-energy neutrinos and photons. The observations have been performed with Carpet-2, a surface air-shower detector equipped with a large-area muon detector at the Baksan Neutrino Observatory in the Northern Caucasus.

LHAASO-KM2A is a sub-array of the Large High Altitude Air Shower Observatory (LHAASO) with an area of kilometer squared scale, consisting of 5195 electromagnetic detectors and 1171 muon detectors. Horizontal Air Showers (HAS) are a fundamental tool to detect penetrating particles like neutrinos and to study hadronic interactions. HAS detected at the ground are mainly constituted by secondary muons. In this contribution first observations of HAS with half array of LHAASO-KM2A are reported. We show that the zenith angle distribution of extensive air showers (EAS) and the transition from electromagnetic-dominated showers to muon-dominated ones above a zenith angle of 60 degree.

LHAASO, located at Daocheng in Sichuan province of China with an altitude up to 4410 m above the sea level, takes the function of hybrid technology to detect cosmic rays. As the major array of LHAASO, KM2A is composed of 5195 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). In the ground-based experiments, there are two common independent data acquisition systems, corresponding to the scaler and shower operation modes. In order to learn more about the scaler mode in LHAASO-KM2A, we adopt the CORSIKA to study the shower development and employ the G4KM2A (based on Geant4) to simulate the detector responses. For one cluster (composed of 64 EDs) in the array of KM2A-ED, the event rates of showers having a number of fired EDs ≥ 1, 2, 3 and 4 (in a time coincidence of 100 ns) are recorded. The average rates of the four multiplicities are ∼ 88 kHz, ∼ 1.4 kHz, ∼ 210 Hz and ∼110 Hz, respectively. For the array of KM2A-MD, there are 16 MDs in one cluster. The average rates with multiplicities ≥ 1 and 2 are ∼ 84 kHz and ∼ 890 Hz, respectively. The corresponding primary energies are also given. According to our simulations, the energy threshold of the scaler mode can be lowered to ∼ 100 GeV. At the same time, the energy threshold of LHAASO-KM2A in shower mode is presented for comparison. The simulation results in this work are beneficial for the online trigger with scaler mode, and also be useful in understanding the experiment results in LHAASO-KM2A.

Title: Half ALPACA and its sensitivity to sub-PeV gamma rays from the Galactic Center Presenter: Yoshichika Yokoe oral/poster: oral Abstract: ALPACA is a project aimed at the wide field-of-view observation of cosmic rays and gamma rays with an 83,000 m^2 air shower array composed of approximately 400 surface scintillation counters and a large underground muon detector array, at an altitude of 4,740m near the Chacaltaya mountain in Bolivia. After a prototype air-shower array currently under construction, we plan to expand the array to ‘half ALPACA’, which covers an area of 83,000 m^2 with roughly 200 surface scintillation counters. Also, we will construct an underground muon detector array with an area of 4,000 m^2 that allows us to dramatically improve the sensitivity to gamma rays by discriminating gamma rays from cosmic rays based on the number of muons in air showers. One of our main interests is the detection of gamma rays beyond 100 TeV from the Galactic center. In 2016, H.E.S.S observed the diffuse gamma-rays around the Galactic center. This data suggests that a cosmic-ray accelerator exists around it. In this presentation, we report on the performance of half ALPACA, especially its sensitivity to sub-PeV gamma rays from the Galactic center, based on our detailed MC simulations.

A set of Cosmic Ray detectors was newly installed in Syowa Station, in the Antarctic, to observe CR neutrons and muons simultaneously at the same location. The observing system has started working in February 2018 and is in stable operation with a high operation rate, >90%. We describe the new systems and show its stability.

In October 2017, a multi-layer small multi-wire (MW) detector for cosmic ray (CR) muon measurements was installed at King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia (Rc = 14.4 GV). This detector is considered to be the first of its kind used for long term CR measurements. In this study, CR data collected from KACST-MW detection system and radiosonde measurements were used to investigate the effect of atmospheric pressure, ground temperature, height of the muon production layer, temperature at that layer, and temperature weighted by atmospheric mass, on CR muons. Regression analyses between the observed muon count rate and these variables were carried out and the corresponding coefficients were obtained and used to correct the observed muon count rate for the temporal variation of these variables. The effect of the atmospheric pressure was conducted first and used to correct the data for this effect. The pressure corrected count rate is anti-correlated with the height of muon production, ground temperature, and atmospheric mass-weighted temperature. On the other hand, the temperature at the muon production layer is positively correlated with the muon count rate. The obtained results from this study are in good agreement with those reported by several researchers. Taking advantages of the relationship between the detected CR muons and the temperature at the muon production layer (stratospheric temperature), this relationship is inverted to calculate this temperature from muon observations. The proposed technique provides excellent predictability of the stratospheric temperatures.

Carpet-2 is an air-shower array at Baksan Valley, Russia, equipped with a large-area (175 m^2) muon detector, which makes it possible to separate primary photons from hadrons. We report the first results of the search for primary photons with energies E_\gamma>1 PeV, directionally associated with IceCube high-energy neutrino events, in the data obtained in 3080 days of Carpet-2 live time., Comment: 6 pages, 2 figures. V2: minor copy-editing changes. Accepted by JETP Letters

Due to confusion in the proof correction process, the author’s proof corrections were not correctly taken into account. The corrections are listed below, highlighted by a boldface font.

Many high schools use QuarkNet cosmic ray muon detectors to learn the scientific process through a variety of experiments investigating cosmic rays. The total solar eclipse of August 21, 2017 provided an opportunity to measure any deviation in secondary cosmic ray flux more than 2 GeV. Students and teachers from high schools near Chicago designed telescopes to carry out measurements of the rate of cosmic ray muons in the direction of the sun during the August 21, 2017 North American solar eclipse. As an independent study project, teams constructed prototypes, measured background rates of muons, and designed two types of telescopes. For four days they operated four types of telescopes in a location where the eclipse was total. It was hypothesized that during a total solar eclipse, the muon flux changes. This research was possible due to an outreach program from QuarkNet, funded by the National Science Foundation.

The present CMS muon system consists of three different detector technologies: drift tubes (DT) and cathode strip chambers (CSC) are used in the barrel and endcap regions of the spectrometer as offline tracking and triggering devices, whereas resistive plate chambers (RPC) are installed both in barrel and endcaps and are exploited mostly in the trigger. To cope with the challenging conditions of increasing luminosity expected at HL-LHC, several upgrades of the muon detectors and trigger system are planned. In the case of DT and CSC, the electronics will be upgraded to handle higher rates, but there is no plan to replace the existing DT, CSC and RPC chambers. Therefore, accelerated ageing tests are being performed to assess the performance stability of all muon detectors under conditions which exceed, by one order of magnitude, the design specifications. New micropattern gas detectors will be added to improve the performance in the forward region, which is characterized by high background rates and a smaller, nonuniform magnetic field. Large-area triple-foil gas electron multiplier (GEM) detectors (GE1/1) are presently being installed during the second LHC long shutdown covering the pseudo-rapidity ($\eta$) region 1.6 < $|\eta|$ < 2.4. They will limit the rate of background triggers, while preserving high trigger efficiency for low transverse momentum muons. For the HL-LHC operation, the muon forward region will also be enhanced with another large area GEM-based station (GE2/1) and with two new generation RPC stations, called RE3/1 and RE4/1, having low resistivity electrodes. These detectors will combine tracking and triggering capabilities and can stand particle rates up to few $kHz/cm^2$.In addition, an ME0 station of GEM chambers will be installed behind the new forward calorimeter to cover up to $|\eta|$ = 2.8 and take advantage of the pixel tracking coverage extension.We present results about the expected performance stability of the existing muon detectors at HL-LHC. Moreover, we report on the outcome of simulation-based studies, which describe the impact of the muon upgrades to the trigger and the reconstruction of muon physics objects.

The CMS muon system at the LHC is built of different detector technologies. The measurement of the background hit rates in the different muon detectors during the LHC Run-2 is of prime importance for an assessment of the longevity of the chambers and their on-board electronics, and therefore for the expected performance of the system at HL-LHC . Moreover, an accurate modelling of the backgrounds using simulations is also critical, as an estimation of the expected radiation background for the Phase-2 upgrade can only rely on Montecarlo-based predictions in the regions where new detectors are being installed. The present understanding of the backgrounds measured with data collected during the LHC Run-2, as well as at CERN high-intensity gamma irradiation facility, GIF++, is discussed, together with the work made to improve the accuracy of the background modelling in Fluka and GEANT4 simulations. The CMS muon system at the LHC is built of different detector technologies. The measurement of the background hit rates in the different muon detectors during the LHC Run-2 is of prime importance for an assessment of the longevity of the chambers and their on-board electronics, and therefore for the expected performance of the system at HL-LHC. Moreover, an accurate modelling of the backgrounds using simulations is also critical, as an estimation of the expected radiation background for the Phase-2 upgrade can only rely on Montecarlo-based predictions in the regions where new detectors are being installed. The present understanding of the backgrounds measured with data collected during the LHC Run-2, as well as at CERN high-intensity gamma irradiation facility, GIF++, is discussed, together with the work made to improve the accuracy of the background modelling in Fluka and GEANT4 simulations.

The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between $$2\times 10^{17}$$2×1017 and $$2\times 10^{18}$$2×1018 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at $$10^{{17.5}}\, {\mathrm{eV}} $$1017.5eV and $$10^{{18}}\, {\mathrm{eV}} $$1018eV. We find that, for the models to explain the data, an increase in the muon density of $$38\%$$38%$$\pm 4\% (12\%)$$±4%(12%)$$\pm {}^{21\%}_{18\%}$$±18%21% for EPOS-LHC, and of $$50\% (53\%)$$50%(53%)$$\pm 4\% (13\%)$$±4%(13%)$$\pm {}^{23\%}_{20\%}$$±20%23% for QGSJetII-04, is respectively needed.

The CMS drift tubes (DT) muon detector, built for standing up the LHC expected integrated and instantaneous luminosities, will be used also in the High Luminosity LHC (HL-LHC) at a 5 times larger instantaneous luminosity and, consequently, much higher levels of radiation, reaching about 10 times the LHC integrated luminosity. Initial irradiation tests of a spare DT chamber at the CERN gamma irradiation facility (GIF++), at large (~O(100)) acceleration factor, showed aging effects resulting in a degradation of the DT cell performance; however, full CMS simulations have shown almost no impact in the muon reconstruction efficiency over the full barrel acceptance and for the full integrated luminosity. A second spare DT chamber was moved inside the GIF++ bunker in October 2017. The chamber was being irradiated at lower acceleration factors, and only 2 out of the 12 layers of the chamber are switched at working voltage when the radioactive source is active, being the other layers in standby. In this way the other non-aged layers are used as reference and as a precise and unbiased telescope of muon tracks for the efficiency computation of the aged layers of the chamber, when set at working voltage for measurements. An integrated dose equivalent to two times the expected integrated luminosity of the HL-LHC run has been absorbed by this second spare DT chamber and the final impact on the muon reconstruction efficiency is under study. Direct inspection of some extracted aged anode wires presented a melted resistive deposition of materials. Investigation on the outgassing of cell materials and of the gas components used at the GIF++ are underway. Strategies to mitigate the aging effects are also being developed. From the long irradiation measurements of the second spare DT chamber, the effects of radiation in the performance of the DTs expected during the HL-LHC run will be presented.

The CMS drift tubes (DT) muon detector, built for withstanding the LHC expected integrated and instantaneous luminosities, will be used also in the High Luminosity LHC (HL-LHC) at a 5 times larger instantaneous luminosity and, consequently, much higher levels of radiation, reaching about 10 times the LHC integrated luminosity. Initial irradiation tests of a spare DT chamber at the CERN gamma irradiation facility (GIF++), at large ($\sim$O(100)) acceleration factor, showed ageing effects resulting in a degradation of the DT cell performance. However, full CMS simulations have shown almost no impact in the muon reconstruction efficiency over the full barrel acceptance and for the full integrated luminosity. A second spare DT chamber was moved inside the GIF++ bunker in October 2017. The chamber was being irradiated at lower acceleration factors, and only 2 out of the 12 layers of the chamber were switched at working voltage when the radioactive source was active, being the other layers in standby. In this way the other non-aged layers are used as reference and as a precise and unbiased telescope of muon tracks for the efficiency computation of the aged layers of the chamber, when set at working voltage for measurements. An integrated dose equivalent to two times the expected integrated luminosity of the HL-LHC run has been absorbed by this second spare DT chamber and the final impact on the muon reconstruction efficiency is under study. Direct inspection of some extracted aged anode wires presented a melted resistive deposition of materials. Investigation on the outgassing of cell materials and of the gas components used at the GIF++ are underway. Strategies to mitigate the ageing effects are also being developed. From the long irradiation measurements of the second spare DT chamber, the effects of radiation in the performance of the DTs expected during the HL-LHC run will be presented., 10 pages, 7 figures, to be published in JINST, editor I. Gonz\'alez Caballero

Aiming to study the primary cosmic-ray mass composition up to the knee energy region with the Tibet underground water-Cherenkov muon-detector array (MD), we propose to extend the dynamic range of each MD detector with an 8-inch PMT (Beijing Hamamatsu CR365) and a 3-inch PMT (HZC XP72B22). We carried out a series of tests on the candidate 3-inch XP72B22 PMT to examine whether it can meet our requirements. The measurement results showed that the XP72B22 has a wide dynamic range of 3 orders of magnitude and a linear response up to ∼105 photoelectrons (PEs) at the supply voltage of 700 V. Combined with previous test results of the CR365, these two types of PMT can achieve an equivalent dynamic range from 30 to 106 PEs. As a result, an MD cell is able to detect cosmic rays around the knee energies by adding the CR365 and the XP72B22.

The $\mu$-RWELL is a new generation Micro-Pattern Gaseous Detector, composed of two elements: the cathode and the $\mu$-RWELL_PCB including the amplification stage, realized with a polyimide structure micro-patterned with a blind-hole matrix, embedded through a Diamond-Like Carbon (DLC) resistive layer with the readout PCB. Different layouts of the resistive stage have been studied: the simplest one is based on a single DLC layer with edge grounding, suitable for low rate applications (30-40 kHz/cm$^{2}$). More sophisticated schemes are under study for high rate purposes (up to 2-3 MHz/cm$^{2}$). The high-rate versions are still under intense R\&D in order to optimize the performance and the constructive process but this detector seems already a valid candidate to be used for the phase 2 upgrade of the LHCb muon detector. For this upgrade, the experiment is targeting a luminosity of 2x10$^{34}$ cm$^{-2}$ s$^{-1}$, with strong requirements on the robustness and detection efficiency of the muon system. We report on the ongoing R&D, showing also the latest measured performances of the new high rate versions of the detector.

著者人数: Tibet ASγ Collaboration 91名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 小財, 正義), Number of authors: Tibet ASγ Collaboration 91 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Kozai, Masayoshi), 資料番号: SA1190109000

The Tibet ASγ experiment located at 4300 m above sea level, Tibet, China, has a wide field of view and large effective area. It consists of the Tibet air-shower array (Tibet-AS), the air-shower core-detector array (YAC) and the underground water-Cherenkov muon-detector array (Tibet- MD). The Tibet-MD array significantly improves its gamma-ray sensitivity in the 10-1000 TeV energy region by an order of magnitude better than any other previous existing experiments in the world. In this paper we will search the γ-ray sources using data taken from 2014. The result shows the direction to the Crab has the most excess in the number of candidate primary γ rays from 3 TeV to 500 TeV. This is the first detection of the highest energy photons beyond 100 TeV from an astrophysical source, and thus opens up the sub-PeV window in astronomy.

We have built a large water Cherenkov muon detector array (Tibet-MD) under the existing Tibet air shower array (Tibet-AS) at 4,300 m above sea level, to observe 10-1000 TeV gamma rays from cosmic-ray accelerators in our Galaxy with wide field of view at very low background level. The Tibet-MD array will improve the sensitivity to gamma-ray sources by an order of magnitude around 100 TeV. In this paper, we will report on the gamma-ray emission from the TeV pulsar wind nebula MGRO J1908+06 observed in the energy region from multi TeV to sub PeV with the Tibet-AS+MD array using data accumulated from 2014.

Muon detector (MD) is water Cherenkov detector in Large High Altitude Air Shower Observatory (LHAASO) experiment. The liner is applied to seal 44 tons of ultra-pure water, which is the major detection media of MD. The liner must protect the water from contamination and inhibit bacteriological activities. The MD conducts a long duration mission (20 years), so any small leak would have severe consequences. The purpose of this paper is to introduce leak test for liners of MDs. A new method of $SF_{6}$ tracer gas leak test is proposed by using a $SF_{6}$ quantitative determination leak detector with high concentration sensitivity (0.01ppm). This method has quick response time and high sensitivity to detect small leak. Since 2018, 300 MDs have been installed, and no leakage has been found till now.

The first stage of LHAASO-KM2A has been completed in Sichuan, China. KM2A is composed of electromagnetic particle detectors (ED) and muon detectors (MD), focusing on gamma ray astronomy above 30 TeV and cosmic ray physics in the “knee” region. The ED array in the first stage is installed into two clusters and the distance between the two clusters is around 230 meters. The MDs are distributed in one of the clusters. Each MD is covered with soil of 2.5 meters thick. We analyzed the lateral distribution of muons which are 140-300 meters away from Shower axis, and the primary cosmic ray energy is about 100TeV.

The Tibet air shower (AS) array and underground water-Cherenkov-type muon detector (MD) array have been successfully operated since 2014, at an altitude of 4,300 m in Tibet, China. we observed 24 gamma-ray events with energy greater than 100 TeV against 5.5 background events, which corresponds to 5.6$\sigma$ statistical significance (Amenomori et al. 2019). The highest energy of the detected gamma rays is estimated to be 450 TeV. This is the first detection of gamma rays beyond 100 TeV from an astrophysical source, and a pioneering work opening a new higher energy window in the astronomy and astrophysics.

We present the results of a search for pulsed gamma-ray emission in the 100 TeV region from several pulsars using data taken with the Tibet air shower (AS) array and a water Cherenkov type muon detector (MD) array. The Tibet AS$¥gamma$ experiment has improved significantly gamma-ray sensitivity by the constructed MD array since 2014. Based on the observational data with the AS + MD array, we will report data on several famous pulsars in the northern hemisphere in this presentation.

Aiming at observing cosmic gamma rays in the energy region beyond several tens of TeV, a water-Cherenkov-type muon detector (MD) array was built under the Tibet air shower (AS) array. The Tibet AS+MD array, which possess high sensitivity to gamma rays beyond 10 TeV, has been operated since 2014. We performed analysis of gamma rays from the Geminga PWN using data collected by the Tibet AS+MD array. We report on the gamma-ray energy spectrum beyond 10 TeV and the morphology of >10 TeV gamma rays.

The CMS experiment uses a sophisticated two-level triggering system composed of hardwarebased Level-1 Trigger, and a software-based High Level Trigger to select 1 kHz of events out of 40 MHz for later analysis. A new Level-1 trigger architecture improves the data taking performance at high luminosity experienced during Run II. The upgraded muon trigger increases the redundancy of the three muon detectors - Cathode Strip Chambers (CSC), Drift Tubes (DT), and Resistive Plate Chambers (RPC) - by combining information in the muon track finders with new track reconstruction, which yields a better efficiency and lower rates. The upgraded muon trigger system and the algorithms designed to select events for both precision measurements and new physics searches are described. The performance of the upgraded muon trigger system is demonstrated using proton-proton collision data collected in Run II.