0000000000017717
AUTHOR
E. Etzelmüller
Recent developments with microchannel-plate PMTs
Abstract Microchannel-plate (MCP) PMTs are the favored photon sensors for the DIRC detectors of the PANDA experiment at FAIR. Until recently the main drawback of MCP-PMTs were serious aging effects which led to a limited lifetime due to a rapidly decreasing quantum efficiency (QE) of the photo cathode (PC) as the integrated anode charge (IAC) increased. In the latest models of PHOTONIS and Hamamatsu an innovative atomic layer deposition (ALD) technique is applied to overcome these limitations. During the last five years comprehensive aging tests with ALD coated MCP-PMTs were performed and the results were compared to tubes treated with other techniques. The QE in dependence of the IAC was m…
Recent progress with microchannel-plate PMTs
Abstract Microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors for the two DIRC detectors of the PANDA experiment at FAIR. As the long-standing aging problem of MCP-PMTs was recently overcome by coating the MCP pores with an atomic layer deposition (ALD) technique, further improved 2 ″ MCP-PMTs were investigated. The best PHOTONIS device has reached a lifetime of > 20 C/cm2 integrated anode charge without any sign of aging. Also the newly developed 2 ″ MCP-PMTs of Hamamatsu are maturing and are usable in high rate environments. The status of our long-term lifetime measurements and the performance parameters of the currently most advanced ALD-coated MCP-PMTs from …
Latest improvements of microchannel-plate PMTS
Abstract The DIRC detectors of the PANDA experiment at FAIR will use multi-anode MCP-PMTs as photon sensors. After long and extensive R&D work the performance parameters of the recent 2” MCP-PMT models are converging towards the required values. The lifetime of most ALD-coated MCP-PMTs is well surpassing the DIRC requirements with the best tube currently reaching > 22 C/cm2 integrated anode charge without aging. The performance of the most advanced MCP-PMTs from PHOTONIS and Hamamatsu fulfill basically all requirements with a highlight being the high detective quantum efficiency (DQE) of almost 30% for the PHOTONIS 9002108. The improvements of the latest MCP-PMT models compared to former tu…
Tremendously increased lifetime of MCP-PMTs
Abstract Microchannel plate (MCP) PMTs are very attractive photon sensors for low light level applications in strong magnetic fields. However, until recently the main drawback of MCP-PMTs was their aging behavior which manifests itself in a limited lifetime due to a rapidly decreasing quantum efficiency (QE) of the photo cathode (PC) as the integrated anode charge (IAC) increases. In the latest models of PHOTONIS, Hamamatsu, and BINP novel techniques are applied to avoid these aging effects which are supposed to be mainly caused by feedback ion impinging on the PC and damaging it. For more than four years we are running a long-term aging test with new lifetime-enhanced MCP-PMT models by sim…
A Disc-DIRC Cherenkov detector with high resolution micro channel plate photomultiplier tubes
The upcoming PANDA Experiment at FAIR in Germany will be equipped with a novel Cherenkov detector type for high-energy particle identification. This very compact Disc-DIRC detector uses a large disc-shaped fused silica plate of 2 cm thickness as its Cherenkov radiator. The internally reflected Cherenkov light is transported to the rim of the disc where it is focused by quartz light guides onto microchannel plate photomultiplier tubes (MCP-PMTs) with high spatial resolution (pitch 0.5 mm) and high time resolution (σ ≈ 100 ps). The device has an active area of about 3 m2 and will be able to identify pions and kaons with a separation power of more than 3σ in the momentum range up to 4 GeV/c. I…
The PANDA DIRC Detectors at FAIR
The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) addresses fundamental questions of hadron physics. An excellent hadronic particle identification (PID) will be accomplished by two DIRC (Detection of Internally Reflected Cherenkov light) counters in the target spectrometer. The design for the barrel region covering polar angles between 22 deg. to 140 deg. is based on the successful BABAR DIRC with several key improvements, such as fast photon timing and a compact imaging region. The novel Endcap Disc DIRC will cover the smaller forward angles between 5 deg. (10 deg.) to 22 deg. in the vertical (horizontal) direction. Both DIRC coun…
The PANDA Barrel DIRC
The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) addresses fundamental questions of hadron physics. Experiments concerning charmonium spectroscopy, the search for hybrids and glueballs and the interaction of hidden and open charm particles with nucleons and nuclei will be performed with antiproton beams impinging on hydrogen or nuclear targets. Cooled beams allow the precision scan of resonances in formation experiments. The momentum range of the antiproton beam between 1.5 GeV/c and 15 GeV/c tests predictions by perturbation theory and will reveal deviations originating from strong QCD . An excellent hadronic particle identificat…
The Endcap Disc DIRC of PANDA
Abstract The Endcap Disc DIRC (EDD) for PANDA has been designed to identify traversing pions, kaons and protons in the future PANDA experiment. Its central part is a 2 cm thick fused silica plate. Focussing optics are attached to the outer rim of the plate, outside of the acceptance of the experiment. Fast, high-resolution MCP-PMTs, designed to register single Cherenkov photons, have been tested in magnetic field. Filters limit the spectral acceptance of the sensors to reduce dispersion effects and to extend their lifetime. A compact and fast readout is realized with ASICs. Analytical reconstruction algorithms allow for fast particle identification. The angular resolution of a DIRC prototyp…
Feasibility study for the measurement of πN transition distribution amplitudes at P¯ANDA in p¯p→J/ψπ0
The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is show…
Tests and developments of the PANDA Endcap Disc DIRC
The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) requires excellent particle identification. Two different DIRC detectors will utilize internally reflected Cherenkov light of charged particles to enable the separation of pions and kaons up to momenta of 4 GeV/c. The Endcap Disc DIRC will be placed in the forward endcap of PANDA's central spectrometer covering polar angles between 5° and 22°. Its final design is based on MCP-PMTs for the photon detection and an optical system made of fused silica. A new prototype has been investigated during a test beam at CERN in May 2015 and first results will be presented. In addition a new synthetic fused silica material…
The PANDA Endcap Disc DIRC
Journal of Instrumentation 13(02), C02002 - C02002 (2018). doi:10.1088/1748-0221/13/02/C02002
The Barrel DIRC detector of PANDA
The PANDA experiment is one of the four large experiments being built at FAIR in Darmstadt. It will use a cooled antiproton beam on a fixed target within the momentum range of 1.5 to 15 GeV/c to address questions of strong QCD, where the coupling constant $\alpha_s \gtrsim 0.3$. The luminosity of up to $2 \cdot 10^{32} cm^{-2}s^{-1}$ and the momentum resolution of the antiproton beam down to \mbox{$\Delta$p/p = 4$\cdot10^{-5}$} allows for high precision spectroscopy, especially for rare reaction processes. Above the production threshold for open charm mesons the production of kaons plays an important role for identifying the reaction. The DIRC principle allows for a compact particle identif…
Breakthrough in the lifetime of microchannel plate photomultipliers
Abstract Cherenkov detectors using the DIRC (Detection of Internally Reflected Cherenkov Light) principle are foreseen for particle identification in the P ¯ ANDA experiment at FAIR. Promising sensors for the detection of the Cherenkov light are the so-called micro-channel plate (MCP) photomultipliers (PMT). They have an excellent time resolution, can be operated at high gain for single photon detection and have a high resistivity against magnetic fields. The disadvantage of these devices was their limited lifetime, due to damage by feedback ions on the photocathode. The lifetime of various types of MCP-PMTs from different manufactures has been tested under conditions similar to that in the…
Development of an Endcap DIRC for PANDA
Abstract The aim of this research is to develop a planar DIRC detector showing advantages and performance similar to a classical, barrel shaped DIRC, but at smaller polar angles which cannot be accessed using a cylindrical geometry. The device will complement the PANDA Barrel DIRC by covering polar angles from 5° to 22°. The envisaged π /K-separation is ≥ 3 σ up to 4 GeV/c. A major challenge is the adaption of the device to the PANDA environment including a magnetic field of ~1–2 T, high rates and radiation, limited space for optics and sensors as well as the lack of a common first-level trigger. This paper discusses a detector design which forms a compromise between these constraints and a…
Study of doubly strange systems using stored antiprotons
Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the PANDA experiment at FAIR. For the first time, high resolution gamma-spectroscopy of doubly strange Lambda Lambda-hypernuclei will be performed, thus complementing measurements of ground state decays of Lambda Lambda-hypernuclei at J-PARC or possible …
Particle Identification with DIRCs at PANDA
The DIRC technology (Detection of Internally Reflected Cherenkov light) offers an excellent possibility to minimize the form factor of Cherenkov detectors in hermetic high energy detectors. The PANDA experiment at FAIR in Germany will combine a barrel-shaped DIRC with a disc-shaped DIRC to cover an angular range of 5 to 140 degrees. Particle identification for pions and kaons with a separation power of 3 standard deviations or more will be provided for momenta between 0.5 GeV/c and 3.5 GeV/c in the barrel region and up to 4 GeV/c in the forward region. Even though the concept is simple, the design and construction of a DIRC is challenging. High precision optics and mechanics are required to…
The PANDA Barrel DIRC
The PANDA experiment at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) 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 barrel region of the PANDA target spectrometer will be provided by a DIRC (Detection of Internally Reflected Cherenkov light) detector. The Barrel DIRC will cover the polar angle range of 22$^\circ$-140$^\circ$ and cleanly separate charged pions from kaons for momenta between 0.5 GeV/c and 3.5 GeV/c with a separation…
Recent results with lifetime enhanced microchannel-plate photomultipliers
Abstract The favored photon sensors for the DIRC (detection of internally reflected Cherenkov light) detectors at the PANDA (Anti-proton Annihilation at Darmstadt) experiment at FAIR (Facility for anti-proton and ion research) are micro-channel-plate photomultipliers (MCP-PMTs). The main problem until a few years ago was the limited lifetime of the MCP-PMTs caused by a rapid decrease in quantum efficiency (QE) of the photo cathode (PC) with increasing integrated anode charge (IAC). These limitations are overcome by applying an atomic layer deposition (ALD) coating on the MCPs, as recently done by PHOTONIS and Hamamatsu. During the last years’ tests of lifetime enhanced MCP-PMTs were perform…
The DIRC detectors at the PANDA experiment
PANDA is an experiment at the new FAIR facility at GSI and will, among other physics goals,\ud perform charmonium spectroscopy and search for gluonic excitations using high luminosity antiproton beams up to 15 GeV/c. A high performance particle identification system applying DIRC\ud detectors will allow pion/kaon separation up to 4 GeV/c. A Barrel DIRC with fused silica radiator bars or plates will surround the target at a radial distance of 48 cm and will cover a polar\ud angle range of 22 to 140 degrees; a novel Endcap Disk DIRC built of a segmented fused silica\ud disk of 210 cm diameter will be installed in the forward region to cover the polar angles from\ud 5 to 22 degrees. The design…
Lifetime of MCP-PMTs and other performance features
The ANDA experiment at FAIR will use DIRC detectors for the separation of hadrons. The compactness of the ANDA detector requires the image planes of these detectors to be placed inside the magnetic field of the solenoid. Due to this and other boundary conditions MCP-PMTs were identified as the only suitable photon sensors. Until recently the major obstacle for an application of MCP-PMTs in high rate experiments like ANDA were serious aging problems which led to damage at the photo-cathode and a fast declining quantum efficiency as the integrated anode charge (IAC) increased. With new countermeasures against the aging, in particular due to the application of an atomic layer deposition (ALD) …
New developments of the PANDA Disc DIRC detector
The DIRC principle (Detection of Internally Reflected Cherenkov light) allows a very compact\ud approach for particle identification detectors. The PANDA detector at the future FAIR facility at\ud GSI will use a Barrel-DIRC for the central region and a Disc DIRC for the forward angular region\ud between 5◦\ud and 22◦\ud . It will be the first time that a Disc DIRC is used in a high performance 4π\ud detector. To achieve this aim, different designs and technologies have been evaluated and tested.\ud This article will focus on the mechanical design and integration of the Disc DIRC with respect to\ud the PANDA environment.
The PANDA DIRC detectors
Abstract The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) will address fundamental questions of hadron physics with unprecedented precision. To reach this goal excellent Particle Identification (PID) is essential over a large range of particle momenta and solid angles. Most of the phase space will be covered by two innovative DIRC (Detection of Internally Reflected Cherenkov light) detectors. The Endcap Disc DIRC and Barrel DIRC will cover the polar angle range from 5 to 22°and 22 to 140°, respectively. Both detectors rely on high precision optical components, lifetime-enhanced Microchannel Plate PMTs (MCP-PMTs), and fast readout electronics.
Resolution changes of MCP-PMTs in magnetic fields
Micro-channel plate photomultiplier tubes (MCP-PMTs) are chosen in many applications that have to cope with strong magnetic fields. The DIRC detectors of the PANDA experiment plan to employ them as they show excellent timing characteristics, radiation hardness, relatively low dark count rates and sufficient lifetime. This article mainly focuses on the performance of the position reconstruction of detected photons. Two different MCP-PMTs with segmented anode geometries have been tested in magnetic fields of different strengths. The variation of their performance has been studied. The measurements show improved position resolution and image shifts with increasing magnetic field strength.
The Endcap Disc DIRC detector of PANDA
Abstract At the international FAIR laboratory, an upcoming significant enlargement of the GSI installations near Darmstadt, Germany, the PANDA antiproton experiment will investigate fundamental questions of hadron physics in the charm quark energy range. Antiprotons in the 1.5 to15 GeV/c momentum range will interact with gas jet or pellet fixed targets. The Endcap Disc DIRC (Detection of Internally Reflected Cherenkov light) covers the forward endcap solid angle of the PANDA target spectrometer to positively identify charged kaons. Monte-Carlo simulations indicate that from 1 up to 4 GeV/c one can achieve kaon–pion separation with a separation power of at least 3 standard deviations. For th…
Particle identification algorithms for the PANDA Barrel DIRC
The International Conference Instrumentation for Colliding Beam Physics , INSTR2020, Novosibirsk, Russia, 24 Feb 2020 - 28 Feb 2020; Journal of Instrumentation 15(09), C09057 (2020). doi:10.1088/1748-0221/15/09/C09057
Time imaging reconstruction for the PANDA Barrel DIRC
The innovative Barrel DIRC (Detection of Internally Reflected Cherenkov light) counter will provide hadronic particle identification (PID) in the central region of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. This detector is designed to separate charged pions and kaons with at least 3 standard deviations for momenta up to 3.5 GeV/c, covering the polar angle range of 22$^{\circ}$-140$^{\circ}$. An array of microchannel plate photomultiplier tubes is used to detect the location and arrival time of the Cherenkov photons with a position resolution of 2 mm and time precision of about 100 ps. The time imaging reconstruction has been develop…
Endcap Disc DIRC for PANDA at FAIR
The Endcap Disc DIRC (EDD) has been developed to provide an excellent particle identification in the future PANDA experiment by separating pions and kaons up to a momentum of 4 GeV/c with a separation power of 3 s.d.. The detector is placed in the forward endcap of the PANDA target spectrometer. It consists of a fused silica plate and focusing elements placed at the outer rim, which focus the Cherenkov light on the photo cathodes of the attached MCP-PMTs. A compact and fast readout of the signals is realized with special ASICs. The performance has been studied and validated with different prototype setups in various testbeam facilities.