Precision Timing Detectors Research Articles

Enhanced long-lived dark photon signals at lifetime frontier detectors

Long-lived particles that are present in many new physics models beyond the standard model, can be searched for in a number of newly proposed lifetime frontier experiments at the LHC. The signals of the long-lived dark photons can be significantly enhanced in a new dark photon model in which dark photons are copiously produced in the hidden radiation process. We investigate the capability of various lifetime frontier detectors in probing the parameter space of this model, including the far forward detectors FACET and FASER, the far transverse detector MATHUSLA, and the precision timing detector CMS-MTD. We find that the accessible parameter space is significantly enlarged by the hidden radiation process so that FACET, MATHUSLA, and CMS-MTD can probe a much larger parameter space than the so-called minimal model. The parameter space probed by FACET is found to be much larger than FASER, which is largely due to the fact that the former has a larger decay volume and is closer to the interaction point. There also exists some parameter space that can be probed both by the far detectors and by precision timing detectors, so that different experiments can be complementary to each other. A brief overview of the lifetime frontier detectors is also given.

Enhanced long-lived dark photon signals at the LHC

We construct a model in which the standard model is extended by a hidden sector with two gauge U(1) bosons. A Dirac fermion ψ charged under both U(1) fields is introduced in the hidden sector which can be a subcomponent of the dark matter in the Universe. Stueckelberg mass terms between the two new gauge U(1) fields and the hypercharge gauge boson mediate the interactions between the standard model sector and the hidden sector. A remarkable collider signature of this model is the enhanced long-lived dark photon events at the LHC than the conventional dark photon models; the long-lived dark photons in the model can be discriminated from the background by measuring the time delay signal in the precision timing detectors which are proposed to be installed in the LHC upgrades and have an mathcal{O} (10) pico-second detection efficiency. Searches with current LHCb data are also investigated. Various experimental constraints on the model including collider constraints and cosmological constraints are also discussed.

High performance timing detectors for high energy physics experiments and new developments for the high luminosity LHC

In recent years precision timing detectors have increasingly captured the interest of the particle physicists, for their potential as time of flight detectors in high luminosity collider experiments as the LHC. In Phase-1 of the LHC, the experiments have exploited a global event description, making use of all subdetector information (tracks, calorimeter hits and muon chamber hits) to optimize the particle energy and position measurement depending on the particle type. This technique usually referred to as “particle flow” has a beneficial effect particularly on the jet energy and on the missing transverse energy resolution. In 2025 a new phase of the Large Hadron Collider will begin with increased instantaneous luminosity (HL-LHC) and a number of concurrent proton-proton interactions per bunch crossing as high as 200. Therefore the events will have very high vertex and track density, and high hit occupancy will be detected in the calorimeters. Hence the need to exploit additional measurement, like the timing information, for the track to vertex matching algorithms and for the association of calorimeter hits to tracks, in order to be able to efficiently use the particle flow technique in these harsher conditions. This lecture reviews the existing detectors with fast and precise timing measurement as well as the physics motivation for their use. It will introduce the various detector technologies able to achieve high performance in timing: Micro-channel plates, scintillation crystals coupled to high gain photodetectors, and silicon based detectors as Low Gain Avalanche devices.

LYSO-based precision timing detectors with SiPM readout

Particle detectors based on scintillation light are particularly well suited for precision timing applications with resolutions of a few 10’s of ps. The large primary signal and the initial rise time of the scintillation light result in very favorable signal-to-noise conditions with fast signals. In this paper we describe timing studies using a LYSO-based sampling calorimeter with wavelength-shifting capillary light extraction and silicon photomultipliers as photosensors. We study the contributions of various steps of the signal generation to the total time resolution, and demonstrate its feasibility as a radiation-hard technology for calorimeters at high intensity hadron colliders.

H4DAQ: a modern and versatile data-acquisition package for calorimeter prototypes test-beams

The upgrade of the particle detectors for the HL-LHC or for future colliders requires an extensive program of tests to qualify different detector prototypes with dedicated test beams. A common data-acquisition system, H4DAQ, was developed for the H4 test beam line at the North Area of the CERN SPS in 2014 and it has since been adopted in various applications for the CMS experiment and AIDA project. Several calorimeter prototypes and precision timing detectors have used our system from 2014 to 2017. H4DAQ has proven to be a versatile application and has been ported to many other beam test environments. H4DAQ is fast, simple, modular and can be configured to support various kinds of setup. The functionalities of the DAQ core software are split into three configurable finite state machines: data readout, run control, and event builder. The distribution of information and data between the various computers is performed using ZEROMQ (0MQ) sockets. Plugins are available to read different types of hardware, including VME crates with many types of boards, PADE boards, custom front-end boards and beam instrumentation devices. The raw data are saved as ROOT files, using the CERN C++ ROOT libraries. A Graphical User Interface, based on the python gtk libraries, is used to operate the H4DAQ and an integrated data quality monitoring (DQM), written in C++, allows for fast processing of the events for quick feedback to the user. As the 0MQ libraries are also available for the National Instruments LabVIEW program, this environment can easily be integrated within H4DAQ applications.

Precision timing detectors with cadmium-telluride sensor

Precision timing detectors for high energy physics experiments with temporal resolutions of a few 10 ps are of pivotal importance to master the challenges posed by the highest energy particle accelerators such as the LHC. Calorimetric timing measurements have been a focus of recent research, enabled by exploiting the temporal coherence of electromagnetic showers. Scintillating crystals with high light yield as well as silicon sensors are viable sensitive materials for sampling calorimeters. Silicon sensors have very high efficiency for charged particles. However, their sensitivity to photons, which comprise a large fraction of the electromagnetic shower, is limited. To enhance the efficiency of detecting photons, materials with higher atomic numbers than silicon are preferable. In this paper we present test beam measurements with a Cadmium-Telluride (CdTe) sensor as the active element of a secondary emission calorimeter with focus on the timing performance of the detector. A Schottky type CdTe sensor with an active area of 1cm2 and a thickness of 1 mm is used in an arrangement with tungsten and lead absorbers. Measurements are performed with electron beams in the energy range from 2 GeV to 200 GeV. A timing resolution of 20 ps is achieved under the best conditions.