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A hadronic calorimeter based on resistive micropattern gaseous detectors
No full textExperiments at future Higgs factories will require excellent energy resolution to discriminate hadronic decays of W/Z and H bosons effectively. To meet this target, calorimeters must feature fine-granularity readouts, essential for implementing the Particle Flow Algorithm (PFA). In this context, an innovative hadronic calorimeter (HCAL) design has been explored, employing resistive Micro Pattern Gaseous Detectors (MPGDs) as active layers. These technologies provide excellent spatial and time resolution, high radiation hardness, and fine-granularity readout, making them ideal for future circular collider experiments optimized for the PFA. This contribution summarizes the results of performance studies conducted on an MPGD-based HCAL standalone Geant4 simulations and benchmarked within the full Muon Collider simulation framework. Results of characterization tests performed with muon beams at the SPS on resistive MPGDs, focusing on efficiency and response uniformity, are also presented. Additionally, the energy response of an HCAL cell prototype is discussed based on beam tests at the PS with pions up to 10 GeV
Not-quite-primordial black holes
No full textWe propose a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to , the Cosmic Microwave Background (CMB) is energetic enough to suppress the formation of molecular hydrogen, hence preventing cooling and fragmentation, as a consequence of which baryons falling into the potential well of the halo may undergo "direct collapse" into a black hole. We show using a few illustrative models how this mechanism may account for the abundance of high-redshift black holes inferred from observations by the while remaining consistent with current limits from CMB spectral distortions. Limits on the primordial power spectrum are also derived by requiring that the universe not reionize too early