The Heavy Photon Search (HPS) Software Environment

Norman Graf,C Doglioni,G.A Stewart,W Kamleh,D Kim,L Silvestris,P Jackson

doi:10.1051/epjconf/202024502018

Norman Graf, C Doglioni + Show 5 more

Open Access

https://doi.org/10.1051/epjconf/202024502018

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Abstract

The Heavy Photon Search (HPS) is an experiment at the Thomas Jefferson National Accelerator Facility (JLab) designed to search for a hidden sector photon (A’) in fixed-target electro-production. It uses a silicon microstrip tracking and vertexing detector placed inside a dipole magnet to measure charged particle trajectories and a fast lead-tungstate crystal calorimeter located just downstream of the magnet to provide a trigger and to identify electromagnetic showers. The HPS experiment uses both invariant mass and secondary vertex signatures to search for the A’. The experimental collaboration is small and quite heterogeneous: it is composed of members of the nuclear physics as well as particle physics communities, from universities and national labs from around the US and Europe. Enabling such a disparate group to concentrate on the physics aspects of the experiment required that the software be easy to install and use, and having such limited manpower meant that existing solutions had to be exploited.HPS has successfully completed two engineering runs and completed its first physics run in the summer of 2019. We begin with an overview of the physics goals of the experiment followed by a short description of the detector design. We then describe the software tools used to design the detector layout and simulate the expected detector performance. Event reconstruction involving track, cluster and vertex finding and fitting for both simulated and real data was, to first order, adopted from existing software originally developed for Linear Collider studies. Bringing it all together into a cohesive whole involved the use of multiple software solutions with common interfaces.

Highlights

There is strong observational evidence for the existence of Dark Matter but its specific nature continues to elude us
If dark photons do couple to electric charge in this way, they will be produced through a process analogous to bremsstrahlung off heavy targets, subsequently decaying to lepton pairs if above the mass threshold for such production
The Heavy Photon Search (HPS) experiment was designed to make use of such a production mechanism to search for a heavy photon decaying into electron-positron pairs using two methods

Summary

Introduction

There is strong observational evidence for the existence of Dark Matter but its specific nature continues to elude us. If dark photons do couple to electric charge in this way, they will be produced through a process analogous to bremsstrahlung off heavy targets, subsequently decaying to lepton pairs if above the mass threshold for such production. The other searches for displaced vertices resulting from long-lived A’ decays Both analyses require fast, robust, high-precision detector elements placed extremely close to a high-intensity electron beam to accumulate high statistics, and to precisely reconstruct the decay products in order to detect and measure any A’ decays above an enormous Standard Model background

Detector Response Simulation

Event Reconstruction

Documentation and Communication

Summary