No Arabic abstract
The facilities designed to study collisions of relativistic nuclei, such as the MPD at NICA (JINR), STAR at RHIC (BNL), ALICE, ATLAS and CMS at the LHC (CERN), are equipped with pairs of hadronic Zero Degree Calorimeters (ZDC) to detect forward nucleons at the both sides of the interaction point and estimate the collision centrality. The energy deposited in a ZDC fluctuates from one event to another, but on average it is proportional to the number of absorbed nucleons. Forward nucleons are also emitted in electromagnetic dissociation (EMD) of nuclei in ultraperipheral collisions, and they are used to monitor the luminosity. As known, ZDC energy spectra are specific to each facility, because they are affected by the ZDC acceptance, and the ZDC energy resolution depends on the beam energy. In this work a simple combinatorial model leading to handy formulas has been proposed to connect the numbers of emitted and detected forward nucleons taking into account a limited ZDC acceptance. The ZDC energy spectra from the EMD with the emission of one, two, three and four forward neutrons and protons have been modeled for collision energies of NICA and the LHC. The case of a rather small ZDC acceptance has been investigated and a possibility to measure the inclusive nucleon emission cross section has been demonstrated.
The calibration and performance of the LHCb Calorimeter system in Run 1 and 2 at the LHC are described. After a brief description of the sub-detectors and of their role in the trigger, the calibration methods used for each part of the system are reviewed. The changes which occurred with the increase of beam energy in Run 2 are explained. The performances of the calorimetry for $gamma$ and $pi^0$ are detailed. A few results from collisions recorded at $sqrt {s}$ = 7, 8 and 13 TeV are shown.
This paper reports the detailed noise characterization, investigation of various noise sources and its mitigation to improve the performance of a cryogenic bolometer detector. The noise spectrum has been measured for a sapphire bolometer test setup with indigenously developed NTD Ge sensor in the CFDR system at Mumbai. The effect of external noise, arising either from ground loops in the system or from the diagnostic and control electronics of the cryostat, on the performance of a cryogenic bolometer is assessed. A systematic comparison of the influence of different noise pickups on the bolometer resolution is also presented. The best-achieved resolution at 15mK is ~15 keV for heater pulses and appears to be mainly limited by the noise due to the pulse tube cryocooler.
The Jiangmen Underground Neutrino Observatory (JUNO) is an experimental project designed to determine the neutrino mass ordering and probe the fundamental properties of the neutrino oscillations. The JUNO central detector is a spherical liquid scintillator detector with a diameter of 35.4 m and equipped with approximately 18,000 20-inch PMTs. A trigger threshold of 0.5 MeV can be easily achieved by using a common multiplicity trigger and can meet the requirements for measuring neutrino mass ordering. However, it is essential to further reduce the trigger threshold for detecting solar neutrinos and supernova neutrinos. A sophisticated trigger scheme is proposed to achieve a low energy threshold by reducing the level of low energy radioactivity and dark noise coincidence. With the new trigger scheme, the events rate of the central detector from different types of sources have been carefully studied by using a detailed detector simulation. It shows that the trigger threshold can be reduced to 0.2 MeV, or even 0.1 MeV, if the concentration of $^{14}$C in liquid scintillator can be well controlled.
The two Zero Degree Calorimeters (ZDCs) of the CMS experiment are located at $pm 140~$m from the collision point and detect neutral particles in the $|eta| > 8.3$ pseudorapidity region. This paper presents a study on the performance of the ZDC in the 2016 pPb run. The response of the detectors to ultrarelativistic neutrons is studied using in-depth Monte Carlo simulations. A method of signal extraction based on template fits is presented, along with a dedicated calibration procedure. A deconvolution technique for the correction of overlapping collision events is discussed.
We present a study which shows encouraging stability of the response linearity for a simulated high granularity calorimeter module reconstructed by a CNN model to miscalibration, bias, and noise effects. Our results also show an intuitive, quantifiable relationship between these factors and the calibration parameters. We trained a CNN model to reconstruct energy in the calorimeter module using simulated single-pion events; we then observed the response of the model under various miscalibration, bias, and noise conditions that affected the model input. From these data, we estimated linear response models to calibrate the CNN. We also quantified the relationship between these factors and the calibration parameters by regression analysis.