High Resolution Beam Telescope Research Articles

Application of material budget imaging for the design of the ATLAS ITk strip detector

The technique of material budget imaging (MBI) allows to experimentally assess the material budget ϵ = x/X 0 of a material with thickness x and its radiation length X 0. Here, multi-GeV electrons from a test beam facility such as the DESY-II test beam are used. This novel technique exploits the fact that the beam particles are deflected by multiple Coulomb scattering following a distribution of the deflection angle with a center at zero and a width depending on the traversed material. By reconstructing the individual kink angles from the measured particle trajectories in a high resolution beam telescope, the material budget can be extracted by applying appropriate models of multiple scattering theory, such as the Highland formula.On the one hand, various materials with known material budgets were measured to calibrate the MBI technique and study also different systematic effects such as the beam telescope’s acceptance and the variation of the beam energy. On the other hand, a number of material samples planned in the design of the local support structures of the new ATLAS Inner Tracker (ITk) strip detector were investigated to extract the according radiation length values not known beforehand.This paper shows therefore the potential of the MBI technique to give an input for the design of high-energy particle detectors by providing experimentally measured numbers of the radiation length for various material compounds with not a-priori known X 0 values.

Lycoris — A large-area, high resolution beam telescope

A high-resolution beam telescope is one of the most important and demanding infrastructurecomponents at any test beam facility. Its main purpose is toprovide reference particle tracks from the incoming test beam particles to thetest beam users, which allows measurement of the performance of the device-under-test (DUT).LYCORIS, a six-plane compact beam telescope with anactive area of ∼ 10 × 10 cm2 (extensible to10× 20 cm2) was installed at the DESY II Test Beam Facility in2019, to provide a precise momentum measurement in a 1 T solenoidmagnet or to provide tracking over a large area.The overall design of Lycoris will be described as well as the performanceof the chosen silicon sensor. The 25 μm pitch micro-stripsensor used for Lycoris was originally designed for the SiD detector conceptfor the International Linear Collider. It adopts a second metallization layerto route signals from strips to the bump-bonded KPiX ASIC and uses a wire-bondedflex cable for the connection to the DAQ and the power supply system. Thisarrangement eliminates the need for a dedicated hybrid PCB. Its performancewas tested for the first time in this project. The system has been evaluatedat the DESY II Test Beam Facility in several test-beam campaigns and has demonstrated an averagesingle-point resolution of 7.07 μm.

Studies of mono-crystalline CVD diamond pixel detectors

Abstract The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in several three layered pixel diamond detectors that are aligned precisely with respect to each other and the beam direction. At a lower rate it also performs particle track position measurements. The PLT's mono-crystalline CVD diamonds are bump-bonded to the same readout chip used in the silicon pixel system in CMS. Mono-crystalline diamond detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. In order to further characterize the applicability of diamond technology to charged particle tracking we performed several tests with particle beams that included a measurement of the intrinsic spatial resolution with a high resolution beam telescope.

First reticule size MAPS with digital output and integrated zero suppression for the EUDET-JRA1 beam telescope

A high resolution beam telescope, based on CMOS monolithic active pixel sensors (MAPS), is being developed within the EUDET collaboration. Mimosa26 is the first pixel sensor covering an active area of ∼224mm2 with integrated zero suppression for this telescope. A single point resolution better than 4μm is expected with a pixel pitch of 18.4μm. The matrix is organised in 576 rows and 1152 columns. At the bottom of the pixel array, each column is connected to an offset compensated discriminator to perform the analogue to digital conversion. Digital data are then treated by a zero suppression circuit in order to send useful information. This architecture allows a fast readout frequency of ∼10kframes/s. The paper concentrates on the details of the chip design and its main performances.

Intermediate Digital Monolithic Pixel Sensor for the EUDET High Resolution Beam Telescope

A high resolution beam telescope, based on CMOS Monolithic Active Pixels Sensors (MAPS), is being developed under the EUDET collaboration, a coordinated detector R&D program for a future international linear collider. A very good spatial resolution < 5 mum, a fast readout time of 100 mus for the whole array (136 times 576 pixels) and a high granularity can be obtained with this technology. A recent fast MAPS chip, designed in AMS CMOS 0.35 mum Opto process with 14 mum epitaxial layer and called MIMOSA22, was submitted to foundry. MIMOSA22 has an active area of 26.5 mm2 with a pixel pitch of 18.4 mum arranged in an array of 576 rows by 136 columns where 8 columns have analog test outputs and 128 have their outputs connected to offset compensated discriminator stages. The pixel array is divided in seventeen blocks of pixels, with different amplification gain, diode size, pixel architecture and is addressed row-wise through a serially programmable (JTAG) sequencer. Discriminators have a common adjustable threshold with internal DAC. MIMOSA22 is the last chip (IDC-Intermediate Digital Chip), before the final sensor of the EUDET-JRA1 beam telescope, which will be installed on the 6 GeV electron beam line at DESY. In this paper, laboratory test results on analog and digital parts are presented. Test beam results, obtained with a 120 GeV pion beam at CERN, are also presented. In the last part of the paper, results on irradiated chips are given.

A high resolution beam telescope built with double sided silicon strip detectors

A compact and portable beam telescope has been built using four 1.92 × 1.92 cm 2 double sided silicon microstrip detectors with 50 μm read-out pitch. Tests using 50 GeV pions have shown that the beam position can be defined with a precision of 5 and 7 μm on the p-side and n-side respectively with an overall detection efficiency of 93.0%.