Detector hardware

This is the written proceeding for the LEAP 2018 Conference, that was held in Paris.
It will be published in 'Hyperfine interaction'. To be sent before May 16, 2018.

The \PANDA experiment is a core project of the future Facility for
Antiproton and Ion Research (FAIR) at GSI in Darmstadt. It will investigate
antiproton-proton annihilations on nucleons and nuclei with the aim to explore fundamental
questions in the non-perturbative regime of QCD as the origin of the hadron mass. The multi-purpose
detector is currently under construction. The intense and high quality anti-proton beam will span
the momentum range between 1.5 and 15 GeV/$c$. Properties of hadrons, leptons, and photons in the final states
will be determined with very high precision. A rich physics program including the study of resonances in the charmonium and open charm region, electromagnetic form factors, and hypernuclear physics is planned. The worldwide collaboration gathers today more than 450 physicists from 60 institutions in 19 countries. An overview of the \PANDA experiment is given, focussing on aspects of the physics program that will be investigated as soon as the facility becomes operational.

PANDA is a hadron physics experiment at the FAIR facility at GSI which will employ a high intensity antiproton beam of up to 15 GeV/c to do high precision studies of, among others, objectives like charmonium spectroscopy and search for gluonic excitations. The measurements require a robust and compact PID system placed inside a magnetic field of $>$1 Tesla with the main components being two DIRC detectors for pion/kaon separation.

Due to the boundary conditions in the focal plane vicinity of the PANDA DIRC detectors microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors. As the long-standing lifetime problem of these devices was overcome recently by employing an atomic layer deposition (ALD) technique to coat the MCP pores, we have investigated further improved and lifetime-enhanced 2-inch MCP-PMTs from PHOTONIS and Hamamatsu. The currently best performing tube is a PHOTONIS XP85112 with two ALD-layers which meanwhile has accumulated close to 20 C/cm$^{2}$ intergrated anode charge (IAC) without any sign of aging. The best of the new Hamamatsu 2-inch MCP-PMT prototypes has reached $>$5 C/cm$^{2}$ without aging.

In addition to the current status of our ongoing lifetime measurements in this talk we will present performance results of the latest hiQE MCP-PMTs with high collection efficiency from PHOTONIS and a new Hamamatsu ALD-coated MCP-PMT without protection film. These are the most advanced commercial MCP-PMTs to date.

We will also present first measurement results obtained with a new quality assurance setup for mass production MCP-PMTs which shall be used to screen all tubes before being installed in the PANDA DIRCs. This setup consists of a 3D-stepper with a PiLas laser and a high performance PADIWA/TRB data aquisition system to measure the response of all anode pixels simultaneously. Among other things this system will allow us to study otherwise difficult to measure background parameters like position dependent dark count rates and ion afterpulsing. Also temporal and spacial distributions of recoil electrons as well as electronic and charge-sharing crosstalk among the anode pixels can be investigated.

PANDA is the main hadron physics addressing experiment of the future FAIR (Facility for Antiproton and Ion Research) center at Darmstadt, Germany. Located at the HESR antiproton storage ring the PANDA detector is optimized for physics of the weak and strong interactions in the charm sector: Search for new and exotic states of matter, precise determination of quantum numbers, masses and widths of hadronic resonances and deeper insights in the structure of hadrons.
The detector consists of a target spectrometer build around the interaction region of antiprotons carrying momenta of 1.5-15 GeV/c with a fixed hydrogen target and a forward spectrometer. Its design is based on compactness and cost saving while achieving high resolution, rate capability and physics selectivity.
In the PANDA target spectrometer the electromagnetic calorimeter is composed of three subdetectors based on at -25 degrees C operated lead tungstate crystals. A barrel structure build from 11360 crystals will be closed in up- and downstream direction by two endcaps containing 524 and 3856 crystals, respectively. After intense beam test phases with a 200 crystal forward endcap prototype the required performance was shown to be met and the design finished. The upstream located forward endcap is currently under construction. Besides the overall mechanical design and cooling concept the 16-crystal submodules series manufacturing and quality assurance measures will be presented.

The PANDA experiment at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR), under construction
near GSI, Darmstadt, Germany, will address fundamental questions of hadron physics.
Excellent Particle Identification (PID) over a large range of solid angles and particle momenta will be essential to meet
the objectives of the rich physics program.
Charged PID for the PANDA target spectrometer will be provided by two innovative RICH counters using the DIRC (Detection of Internally
Reflected Cherenkov light) technology.

The Barrel DIRC will cover the polar angle range of 22-140 degrees and cleanly separate charged pions from kaons for momenta
between 0.5 GeV/c and 3.5 GeV/c with a separation power of at least 3 standard deviations (s.d.).
The design is based on the successful BABAR DIRC and the SuperB FDIRC R&D with several important improvements to optimize
the performance for PANDA, such as wider and shorter radiator bars, a spherical focusing lens system, fast timing, a compact
fused silica prism as expansion region, and lifetime-enhanced Microchannel-Plate PMTs (MCP-PMTs) for photon detection.

The Endcap Disc DIRC (EDD) will separate pions from kaons with momenta up to 4 GeV/c and polar angles between 5 and 22 degrees
with a separation power of 3 s.d. or more.
The EDD consists of four optically isolated quadrants, each comprising a synthetic fused silica radiator plate of 2 cm
thickness, focusing optics along the outer edge to convert the angle information into a position information, and a compact
readout region.
The intrinsic contribution of a chromatic error is reduced by an optical filter and an adapted photocathode.
High-resolution MCP-PMTs will be used in connection with a fast ASIC-based readout to record events.

We will discuss the technical design of the two PANDA DIRC detectors and the results of the design validation using
prototypes in hadronic particle beams at DESY and at CERN.

PANDA Management Quarterly Report 18Q1

This document is the Technical Design Report covering the Muon System of the PANDA detector consisting of four parts, the Barrel, the End Cap the Muon Filter and the Forward Range System. It describes the design of the full Muon System equipped with Mini Drift Tube detectors with corresponding electronics and their expected performance. The actual realization may be subjected to possible modifications arising during the tendering process and in the final construction.

This document forms part of the PANDA Technical Design Report and covers the cluster-jet and the pellet targets. The former one is already fully developed and will be the day-1 PANDA target for commissioning and medium luminosity experiments. Higher effective target densities can be achieved with a frozen pellet target including a pellet tracking system for vertex reconstruction.
The technical design of the pellet generator will be described in a forthcoming appendix to this document.