The radiation pattern within high energy quark- and gluon-initiated jets (jet substructure) is used extensively as a precision probe of the strong force as well as an environment for optimizing event ...generators with numerous applications in high energy particle and nuclear physics. Looking at electron-proton collisions is of particular interest as many of the complications present at hadron colliders are absent. A detailed study of modern jet substructure observables, jet angularities, in electron-proton collisions is presented using data recorded using the H1 detector at HERA. The measurement is unbinned and multi-dimensional, using machine learning to correct for detector effects. All of the available reconstructed object information of the respective jets is interpreted by a graph neural network, achieving superior precision on a selected set of jet angularities. Training these networks was enabled by the use of a large number of GPUs in the Perlmutter supercomputer at Berkeley Lab. The particle jets are reconstructed in the laboratory frame, using the kT jet clustering algorithm. Results are reported at high transverse momentum transfer Q2>150GeV2, and inelasticity 0.2<y<0.7. The analysis is also performed in sub-regions of Q2, thus probing scale dependencies of the substructure variables. The data are compared with a variety of predictions and point towards possible improvements of such models.
The PILATUS 1M detector Broennimann, Ch; Eikenberry, E. F.; Henrich, B. ...
Journal of synchrotron radiation,
03/2006, Letnik:
13, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The PILATUS 1M detector is a hybrid pixel array detector with over one million pixels that operate in single photon counting mode. The detector, designed for macromolecular crystallography, is the ...largest pixel array detector currently in use at a synchrotron. It is a modular system consisting of 18 multichip modules covering an area of 21 cm × 24 cm. The design of the components as well as the manufacturing of the detector including the bump‐bonding was performed at the Paul Scherrer Institute (PSI). The use of a single photon counting detector for protein crystallography requires detailed studies of the charge collection properties of the silicon sensor. The 18 modules are read out in parallel, leading to a full frame readout‐time of 6.7 ms. This allows crystallographic data to be acquired in fine‐ϕ‐slicing mode with continuous rotation of the sample. The detector was tested in several experiments at the protein crystallography beamline X06SA at the Swiss Light Source at PSI. Data were collected both in conventional oscillation mode using the shutter, as well as in a fine‐ϕ‐slicing mode. After applying all the necessary corrections to data from a thaumatin crystal, the processing of the conventional data led to satisfactory merging R‐factors of the order of 8.5%. This allows, for the first time, determination of a refined electron density map of a macromolecular biological crystal using a silicon pixel detector.
The hybrid pixel detectors used in the high-energy physics experiments currently under construction use a vertical connection technique, the so-called bump bonding. As the pitch below
100
μ
m
, ...required in these applications, cannot be fulfilled with standard industrial processes (e.g. the IBM C4 process), an in-house bump bond process using reflowed indium bumps was developed at PSI as part of the R&D for the CMS-pixel detector.
The bump deposition on the sensor is performed in two subsequent lift-off steps. As the first photolithographic step a thin under bump metalization (UBM) is sputtered onto bump pads. It is wettable by indium and defines the diameter of the bump. The indium is evaporated via a second photolithographic step with larger openings and is reflowed afterwards. The height of the balls is defined by the volume of the indium. On the readout chip only one photolithographic step is carried out to deposit the UBM and a thin indium layer for better adhesion. After mating both parts a second reflow is performed for self-alignment and obtaining high mechanical strength.
For the placement of the chips a manual and an automatic machine were constructed. The former is very flexible in handling different chip and module geometries but has a limited throughput while the latter features a much higher grade of automatization and is therefore much more suited for producing hundreds of modules with a well-defined geometry.
The reliability of this process was proven by the successful construction of the PILATUS detector. The construction of PILATUS 6M (60 modules) and the CMS pixel barrel (roughly 800 modules) has started in early 2006.
Design and performance of the CMS pixel detector readout chip Kästli, H.Chr; Barbero, M.; Erdmann, W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2006, Letnik:
565, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The readout chip for the CMS pixel detector has to deal with an enormous data rate. On-chip zero suppression is inevitable and hit data must be buffered locally during the latency of the first level ...trigger. Dead-time must be kept at a minimum. It is dominated by contributions coming from the readout. To keep it low an analog readout scheme has been adopted where pixel addresses are analog coded.
We present the architecture of the final CMS pixel detector readout chip with special emphasis on the analog readout chain. Measurements of its performance are discussed.
Abstract Exclusive photoproduction of $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900,000 events is used to measure single- ...and double-differential cross sections for the reaction $$\gamma p \rightarrow \pi ^{+}\pi ^{-}Y$$ γ p → π + π - Y . Reactions where the proton stays intact ( $${{{m_Y}} {=}m_p}$$ m Y = m p ) are statistically separated from those where the proton dissociates to a low-mass hadronic system ( $$m_p{<}{{m_Y}} {<}10~{{\text {GeV}}} $$ m p < m Y < 10 GeV ). The double-differential cross sections are measured as a function of the invariant mass $$m_{\pi \pi }$$ m π π of the decay pions and the squared 4-momentum transfer t at the proton vertex. The measurements are presented in various bins of the photon–proton collision energy $${{W_{\gamma p}}} $$ W γ p . The phase space restrictions are $$0.5\le m_{\pi \pi } \le 2.2~{{\text {GeV}}} $$ 0.5 ≤ m π π ≤ 2.2 GeV , $$\vert t\vert \le 1.5~{{\text {GeV}^2}} $$ | t | ≤ 1.5 GeV 2 , and $$20 \le W_{\gamma p} \le 80~{{\text {GeV}}} $$ 20 ≤ W γ p ≤ 80 GeV . Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the $${m_{\pi \pi }}$$ m π π dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) meson mass and width at $$m_\rho = 770.8{}^{+2.6}_{-2.7}~({\text {tot.}})~{{\text {MeV}}} $$ m ρ = 770.8 - 2.7 + 2.6 ( tot. ) MeV and $$\Gamma _\rho = 151.3 {}^{+2.7}_{-3.6}~({\text {tot.}})~{{\text {MeV}}} $$ Γ ρ = 151.3 - 3.6 + 2.7 ( tot. ) MeV , respectively. The model is used to extract the $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) contribution to the $$\pi ^{+}\pi ^{-}$$ π + π - cross sections and measure it as a function of t and $${W_{\gamma p}}$$ W γ p . In a Regge asymptotic limit in which one Regge trajectory $$\alpha (t)$$ α ( t ) dominates, the intercept $$\alpha (t{=}0) = 1.0654\ {}^{+0.0098}_{-0.0067}~({\text {tot.}})$$ α ( t = 0 ) = 1.0654 - 0.0067 + 0.0098 ( tot. ) and the slope $$\alpha ^\prime (t{=}0) = 0.233 {}^{+0.067 }_{-0.074 }~({\text {tot.}}) ~{{\text {GeV}^{-2}}} $$ α ′ ( t = 0 ) = 0.233 - 0.074 + 0.067 ( tot. ) GeV - 2 of the t dependence are extracted for the case $$m_Y{=}m_p$$ m Y = m p .
Mythen detector system Schmitt, B; Brönnimann, Ch; Eikenberry, E.F ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
501, Številka:
1
Journal Article
Recenzirano
Time-resolved experiments in powder diffraction are limited by the long time required to record spectra with current detectors. A major improvement can be made by using a massively parallel X-ray ...detection system together with a fast read out. The Mythen detector (Microstrip system for time-resolved experiments) has been built for the Powder Diffraction Station of the Material Science beamline at the Swiss Light Source to meet these requirements. The specifically developed read out chip (Mythen chip), the detector system and first measurements are shown.
The CMS experiment at the (LHC) includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The barrel region consists of n-in-n sensors with
...100
×
150
μ
m
2
cell size processed on diffusion oxygenated float zone silicon. A biasing grid is implemented and pixel isolation is achieved with the moderated p-spray technique. An extensive test program was carried out on the H
2 beam line of the CERN-SPS. In this paper we describe the sensor layout, the beam test setup and the results obtained with both irradiated and non-irradiated prototype devices. Measurements of charge collection, hit detection efficiency, Lorentz angle and spatial resolution are presented.
A large quantum-limited area X-ray detector for protein crystallography is under development at the Swiss Light Source. The final detector will be 2k×2k pixels covering
40×40
cm
2
. A three-module ...prototype with 1120×157 pixels covering an active area of
24.3×3.4
cm
2
has been tested. X-rays above
6
keV
with peak count rates exceeding 5×10
5 X-ray/pixel/s could be detected in single photon counting mode. Statistics of module production and results of threshold trimming are presented. To demonstrate the potential of this new detector, protein crystal data were collected at beamline 6S of the SLS.
Development of single photon counting detectors at the Swiss Light Source Schmitt, B.; Brönnimann, Ch; Eikenberry, E.F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
To optimally use the high flux delivered by current, third-generation synchrotron radiation sources like the Swiss Light Source at the Paul Scherrer Institute two detector systems are currently being ...developed. The Mythen detector system is a one-dimensional 15k channel microstrip detector for powder diffraction. It allows major improvement in time-resolved powder diffraction due to its massively parallel detection of X-rays and fast readout. The Pilatus detector is a 2k × 2k pixel detector for protein crystallography. Its advantages compared to current state-of-the-art CCDs are a much better signal-to-noise ratio, a point spread function of 1 pixel and a very short readout time of 6.7
ms. This allows data to be taken in fine
φ-slicing mode which will improve the data quality.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS ...collaborations at HERA for neutral and charged current ... scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb... and span six orders of magnitude in negative four-momentum-transfer squared, ..., and Bjorken x. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in ... An extraction of ... and results on electroweak unification and scaling violations are also presented.
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