Growing energies of particles at modern or planned particle accelerator experiments as well as cosmic ray experiments require particle identification at gamma-factors (γ) of up to ∼105. At present ...there are no detectors capable of identifying charged particles with reliable efficiency in this range of γ. New developments in high granular pixel detectors allow one to perform simultaneous measurements of the energies and the emission angles of generated transition radiation (TR) X-rays and use the maximum available information to identify particles. First results of studies of TR energy-angular distributions using gallium arsenide (GaAs) sensors bonded to Timepix3 chips are presented. The results are compared with those obtained using a silicon (Si) sensor of the same thickness of 500 μm. The analysis techniques used for these experiments are discussed.
Abstract
This work presents the development of a front-end simulation code for the Timepix3 readout chip 1, intended as digitizer stage in full detector simulation. The front-end electronics is ...modelled using an integrator stage and 3 parallel feedback loops with individually configurable time constants. The main feedback discharging the integrator consists of 3 low-pass filtered feedback loops. The leakage current compensation is approximated by an additional independent low-pass filtered feed-back loop. The system noise is modelled using independent bandwidth limited noise channels for pre-amplifier, feedback and threshold noise. The Timepix3 time of arrival (ToA) and time over threshold (ToT) measurement is implemented by a discriminator model with independent rise and fall times and 2 independent clock frequencies for ToA and ToT. The measured dependence of the ToT on the pre-amplifier input charge using test-pulses of a Timepix3 assembly is correctly reproduced for a wide range of discriminator settings.
We performed a detailed study of the timing performance of the LHCb VELO Timepix3 Telescope with a 180 GeV/c mixed hadron beam at the CERN SPS. A twofold method was developed to improve the ...resolution of single-plane time measurements, resulting in a more precise overall track time measurement. The first step uses spatial information of reconstructed tracks in combination with the measured signal charge in the sensor to correct for a mixture of different effects: variations in charge carrier drift time; variations in signal induction, which are the result of a non-uniform weighting field in the pixels; and lastly, timewalk in the analog front-end. The second step corrects for systematic timing offsets in Timepix3 that vary from −2 to 2 ns. By applying this method, we improved the track time resolution from 438(16) ps to 276(4) ps.
New developments of pixel detectors based on GaAs sensors offer effective registration of the transition radiation (TR) X-rays and perform simultaneous measurements of their energies and emission ...angles. This unique feature opens new possibilities for particle identification on the basis of maximum available information about generated TR photons. Results of studies of TR energy-angular distributions using a 500 |j.m thick GaAs sensor attached to a Timepix3 chip are presented. Measurements, analysis techniques and a comparison with Monte Carlo (MC) simulations are described and discussed.
A novel monolithic pixelated sensor and readout chip, the compact linear collider tracker detector (CLICTD) chip, is presented. The CLICTD chip was designed targeting the requirements of the silicon ...tracker development for the experiment at the compact linear collider (CLIC) and has been fabricated in a modified 180 nm CMOS imaging process with charge collection on a high-resistivity p-type epitaxial layer. The chip features a matrix of <inline-formula> <tex-math notation="LaTeX">16\times 128 </tex-math></inline-formula> elongated channels, each measuring <inline-formula> <tex-math notation="LaTeX">300\times 30\,\,\mu \text {m}^{2} </tex-math></inline-formula>. Each channel contains 8 equidistant collection electrodes and analog readout circuits to ensure prompt signal formation. A simultaneous 8-bit time-of-arrival (with 10 ns time bins) and 5-bit time-over-threshold measurement is performed on the combined digital output of the 8 subpixels in every channel. The chip has been fabricated in two process variants and characterized in laboratory measurements using electrical test pulses and radiation sources. Results show a minimum threshold between 135 and 180 e − and a noise of about 14 e − rms. The design aspects and characterization results of the CLICTD chip are presented.
A novel approach for the readout of a TPC at the future linear collider is to use a CMOS pixel detector combined with some kind of gas gain grid. A first test using the photon counting chip Medipix2 ...with GEM or Micromegas demonstrated the feasibility of such an approach. Although this experiment demonstrated that single primary electrons could be detected the chip did not provide information on the arrival time of the electron in the sensitive gas volume nor did it give any indication of the quantity of charge detected. The Timepix chip uses an external clock with a frequency of up to 100
MHz as a time reference. Each pixel contains a preamplifier, a discriminator with hysteresis and 4-bit DAC for threshold adjustment, synchronization logic and a 14-bit counter with overflow control. Moreover, each pixel can be independently configured in one of four different modes: masked mode: pixel is off, counting mode: 1-count for each signal over threshold, TOT mode: the counter is incremented continuously as long as the signal is above threshold, and arrival time mode: the counter is incremented continuously from the time the first hit arrives until the end of the shutter. The chip resembles very much the Medipix2 chip physically and can be readout using slightly modified versions of the various existing systems. This paper presents the main features of the new design, electrical measurements and some first images.
More than 10 years experience with semiconductor pixel detectors for vertex detection in high-energy physics experiments together with the steady progress in CMOS technology opened the way for the ...development of single photon processing pixel detectors for various applications including medical X-ray imaging. The state of the art of such pixel devices consists of pixel dimensions as small as
55×55
μm
2
, electronic noise per pixel
<100
e
−
rms
, signal-to-noise discrimination levels around
1000
e
−
with a spread
<50
e
−
and a dynamic range up to 32 bits/pixel. Moreover, the high granularity of hybrid pixel detectors makes it possible to probe inhomogeneities of the attached semiconductor sensor.
We performed a detailed study of the timing performance of the LHCb VELO Timepix3 Telescope with a 180 GeV/c mixed hadron beam at the CERN SPS. A twofold method was developed to improve the ...resolution of single-plane time measurements, resulting in a more precise overall track time measurement. The first step uses spatial information of reconstructed tracks in combination with the measured signal charge in the sensor to correct for a mixture of different effects: variations in charge carrier drift time; variations in signal induction, which are the result of a non-uniform weighting field in the pixels; and lastly, timewalk in the analog front-end. The second step corrects for systematic timing offsets in Timepix3 that vary from -2 ns to 2 ns. By applying this method, we improved the track time resolution from 438\(\,\pm\,\)16 ps to 276\(\,\pm\,\)4 ps.
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