Session U08: Detector R&D and performance II

Incorporating position sensitivity into an E x B design microchannel plate detector

Many radioactive beam experiments whether utilizing fast or reaccelerated beams benefit from imaging the beam continuously through the experiment. Moreover, providing position information on a particle-by-particle basis allows tracking which reduces the angular uncertainty. Such capability can be realized by using an ExB microchannel plate detector (MCP). Passage of a single ion through a thin secondary emission foil generates electrons that are transported to an MCP by the crossed electric and magnetic fields. Simulations with the ion transport code SIMION demonstrate that the image of the beam on the secondary emission foil is largely preserved in one dimension through the electron transport. To make the MCP position sensitive, the standard metal anode was replaced with a multi-strip anode. Strips in the anode, which collect the electron cloud, are coupled to a delay line. The time difference between the arrival of the signal at either end of the delay line provides the position information. In this talk the design, construction, and commissioning of the detector will be described. Simulations that describe the electron transport and determine the position resolution achieveable will be presented.   

A Search for New Physics using Trigger-Level Analysis with ATLAS

Dijet events with invariant masses below 1 TeV are studied in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector for possible signs of new physics produced at the Large Hadron Collider. Searches for dijet resonances in this mass range are difficult because large Standard Model multijet backgrounds, combined with DAQ bandwidth constraints, force restrictions on the amount of data that may be collected. The Trigger-Level Analysis (TLA) technique solves this problem by recording partial events that contain only the subset of full event data that is necessary for the dijet search. This talk describes a search for new physics using TLA techniques to analyze dijet events, highlighting work done to study the performance of physics objects contained in partial events. Results from the most recent publications are presented.   

Single Top + Higgs$\rightarrow b\bar{b}$ Production in ATLAS Experiment: Investigating Effect of High Granularity Timing Detector (HGTD) on Analysis with Phase II Upgrade

In 2022, the Large Hadron Collider (LHC) will undergo a High Luminosity (HL) Phase-II Upgrade, which will increase the instantaneous luminosity of the LHC by as much as a factor of 10. The ATLAS detector, operating at the LHC, will be upgraded in preparation for the high luminosity environment. As part of the upgrade, a High Granularity Timing Detector (HGTD) is proposed to be placed near the endcaps of the cylindrical ATLAS detector. The HGTD would record the time-of-flight of particles from the main proton-proton collision with a resolution of 30 ps. We conduct a physics analysis of single top + Higgs $\rightarrow bb$ production, or tH, to investigate the impact of the HGTD on the significance of tH compared to its ttbar background. The tH decay mode is relevant because it can help determine both the sign and magnitude of Yukawa coupling between the Higgs boson and top quark. It is also highly sensitive to deviations of the tH cross section from its Standard Model value, meaning there is potential to observe new physics through this channel. In our analysis, we compare tH significance before and after including the HGTD in the simulation. We find that implementing the HGTD with features such as a forward electron trigger could increase tH significance by as much as 13\%.   

Ultra-Fast Hadronic Calorimetry

Calorimeters for particle physics experiments with integration time of a few ns will substantially improve the capability of the experiment to resolve event pileup and to reject backgrounds. In this presentation time development of hadronic showers induced by 30 and 60 GeV positive pions and 120 GeV protons is presented using Monte Carlo simulation and beam tests with a prototype of a sampling steel-scintillator hadronic calorimeter. In the beam tests, scintillator signals induced by hadronic showers in steel are sampled with a period of 0.2 ns and precisely time-aligned in order to study the average signal waveform at various locations w.r.t. the beam particle impact. Simulations of the same setup are performed using the MARS15 code. Both simulation and test beam results suggest that energy deposition in steel calorimeters develop over a time shorter than 3 ns providing opportunity for ultra-fast calorimetry. Simulation results for an ``ideal'' calorimeter consisting exclusively of bulk tungsten or copper are presented to establish the lower limit of the signal integration window.   

Mistag rate calibration using Direct Tag method in {\$}pp{\$} collisions at {\$}$\backslash $sqrt\textbraceleft s\textbraceright $=${\$} 13 TeV with the ATLAS detector

The efficient identification of jets from bottom quarks (b-jets) is one of the most important techniques for many physics analyses at the Large Hadron Collider, including studies of the Higgs boson, the top quark, and searches beyond the Standard Model. The performance is characterized by b-tagging efficiency (probability to identify a b-jet as such) and the mistag rate (probability to mistakenly accept a non-b-jet).The mistag occurs as a result of finite detector resolution, presence of long-lived particles, and material interactions. As these effects can be different between the experimental data and Monte Carlo (MC) simulation, it is important to measure the b-tagging performance in data and derive the MC correction factors.I will be describing Direct Tag method which is recently developed in the ATLAS collaboration for mistag rate calibration and I will present some of its results using the latest dataset in {\$}pp{\$} collisions at {\$}$\backslash $sqrt\textbraceleft s\textbraceright $=${\$} 13 TeV with the ATLAS detector.   

Heterodyne Design for ALPS II experiment

The Any Light Particle Search II (ALPS II) is a Light Shining through Walls (LSW) experiment which searches for axions and axion-like particles which couple to photons in the presence of a high magnetic field. The ALPS project develops two different detection methods. One is a classical photon counting technique which uses a cryogenic transition edge sensor. The heterodyne (HET) detection technique takes advantage of the spatial and temporal coherence of the regenerated electromagnetic field with the initial generating laser field and is currently being developed in our laboratories at the University of Florida. I will report on the tests and design work of the optical bench for HET which address issues related to coherent control and stray light.   

Single Photon Detection Using Optical Heterodyne Interferometry

The coherent coupling between an electro-magnetic laser field and the axion or axion-like particle field inside a strong magnetic field is utilized by the ALPS collaboration to search for axions and axion-like particles. The proposed heterodyne detection method uses this coherence to search for a signal in a shot noise limited local oscillator field. This method has a high quantum efficiency and avoids typical limitations due to dark count rates and offers an improvement over classical photon counting detection methods. We built a testbed to study and develop this sensing scheme for ALPS. Our initial results of an equivalent dark count rate of better than $10^{-6}$/s and successful test experiments detecting photons at a rate of $10^{-2}$/s will be presented. We will also discuss potential future improvements.   

First application of a novel directional neutron detector to background measurements at SuperKEKB.

During first commissioning of the SuperKEKB accelerator, the next-generation B factory located in Tsukuba, Japan, the BEAST II commissioning detector conducted measurements of beam induced backgrounds. Such backgrounds are critical as they will eventually limit both the accelerator beam life time and performance and longevity of the Belle II detector. Among the many measurements made by the BEAST II system, the Micro Time Projection Chambers (micro-TPCs) subsystem provided the first observations of fast neutrons generated by the various beam backgrounds. We present motivations for fast neutron measurements at SuperKEKB and Belle II commissioning, a detailed description of the micro-TPC subsystem, and the resulting 3D tracking and charge cloud measurements of fast neutron recoils in a helium/carbon dioxide target gas and compare the resulting data with expectations from dedicated beam-loss and detector simulations. If time allows, we also present beam background measurements and conclusions from other BEAST II efforts.   

Experimental demonstration of enhancement in sensitivity to axionic dark matter using a squeezed state receiver

D. A. Palken, M. Malnou, L. R. Vale, G. C. Hilton, and K. W. Lehnert$\backslash $Squeezed states of the microwave field can be used to reduce the noise in haloscope-based axion detection of the type performed by HAYSTAC [1, 2]. Using a Josephson parametric amplifier (JPA), we generate a squeezed state, inject it into an overcoupled dummy axion cavity, and, upon readout with a second JPA, observe significant improvement in the contrast of a pseudo-axion tone above a background of vacuum noise. We then characterize the time to infer the presence or absence of a weak pseudo-axion signal, and how this time is reduced with squeezing. $\backslash $[1] Zheng, H. \textit{et al.} Preprint at https://arxiv.org/abs/1607.02529 (2016).2] Brubaker, B. \textit{et al}. First Results from a Microwave Cavity Axion Search at 24 $\mu $eV. \textit{Phys. Rev. Lett.} \textbf{118}, 061302 (2017).