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The ALPHA collaboration, based at CERN, has recently succeeded in confining cold antihydrogen atoms in a magnetic minimum neutral atom trap and has performed the first study of a resonant transition of the anti-atoms. The ALPHA apparatus will be described herein, with emphasis on the structural aspects, diagnostic methods and techniques that have enabled antihydrogen trapping and experimentation to be achieved. © 2013 Elsevier B.V.

We report our experience commissioning and operating the CDF Run II silicon detector during the first three years of Run II. The performance of the system and its impact on physics analysis are reviewed. As the luminosity delivered by the Tevatron increases, measurable effects of radiation damage have been observed. Studies of charge collection and noise versus applied bias voltage at several different integrated luminosities are presented. These results and their impact on the expected lifetime of the detector are discussed. (c) 2005 Elsevier B.V. All rights reserved.

Over the last decades the experiments in elementary particle physics at the new colliding beam accelerators with TeV energy, in particular the LHC at CERN, have seen profound changes. These present orders of magnitude increases in physical size, interaction rates, radiation intensity and data volume. Not only new instruments such as segmented and pixelated silicon detectors, but also calorimeters and surrounding muon detectors feature a much larger number of sensing elements. This provides improved precision in particle tracking and momentum measurement, avoiding a need for even larger overall detector dimensions. Associated silicon integrated circuits, specifically designed for these applications, improve the speed and reduce the electrical power for signal processing and information extraction. Now the detectors can cope with near-GHz interaction rates, more than 1000-fold the rate at the LEP collider ∼ 1995, and produce distinctive reconstructions of interactions with μ m-level precision, even with hundreds of simultaneous particles. All this in the inherently severe radiation environment up to tens of Mrad. The unconventional exploitation of silicon chip technology for radiation sensing and large-scale parallel signal processing has been the most important enabling factor. Some of the successive steps in the introduction of the silicon devices are described here in a narrative way, and with an unavoidable personal bias of the author. General characteristics of this electronics are outlined, including a brief description of IC manufacturing technologies. The focus is on the inner vertexing and tracker systems, which profited most of the miniaturization. References are made to further articles in the special issue, which treat in more detail the instruments and associated circuits for readout, precision timing and voluminous data transmission, by wire or optical fiber. In the margin, historical circumstances are indicated, which made the 'silicon revolution' possible and affordable for high energy physics. • Silicon technology and ASIC design in the physics research community are a key to discovery. • Some of the historical steps are described in the introduction of microelectronics. • Invention of new instruments often comes by serendipity, instead as planned development. [ABSTRACT FROM AUTHOR]

The "chip-on-sensor" concept of this detector minimizes the distance of the signal propagation from the double-sided silicon detector strips to the readout chips and thus reduces noise from strip capacitance. One half of the detector is built, the second half is being assembled at the time of writing. Prototypes have been tested in several test beams as well as in the so-called Phase 2 setup inside the detector structure. First results from a commissioning run of the Belle-II prototype SVD detector are presented. The measured signal-to-noise and timing performance are found to be according to design specifications. • The Belle-II Silicon Vertex Detector is based on a "chip-on-sensor" concept. • One half of the detector is built, the second half is being assembled. • Prototypes have been tested in a commissioning run inside the detector structure. • The measured SNR and hit time are found to be according to design specifications. [ABSTRACT FROM AUTHOR]

The silicon vertex detector of the Belle II experiment, structured in a lantern shape, consists of four layers of ladders, fabricated from two to five silicon sensors. The APV25 readout ASIC chips are mounted on one side of the ladder to minimize the signal path for reducing the capacitive noise; signals from the sensor backside are transmitted to the chip by bent flexible fan-out circuits. The ladder is assembled using several dedicated jigs. Sensor motion on the jig is minimized by vacuum chucking. The gluing procedure provides such a rigid foundation that later leads to the desired wire bonding performance. The full ladder with electrically functional sensors is consistently completed with a fully developed assembly procedure, and its sensor offsets from the design values are found to be less than 200 μm. The potential functionality of the ladder is also demonstrated by the radioactive source test. [ABSTRACT FROM AUTHOR]

This paper describes an investigation into gluing and wire bonding for assembling the Silicon Vertex Detector (SVD) for the Belle II experiment at KEK in Japan. Optimizing the gluing of the silicon microstrip sensors, the support frame, and the readout flex cables is important for achieving the required mechanical precision. The wire bonding between the sensors and the readout electronic chips also needs special care to maximize the physics capability of the SVD. The silicon sensors and signal fan out flex circuits (pitch adapters) are glued and connected using wire bonding. We determine that gluing quality is important for achieving good bonding efficiency. The standard deviation in the glue thickness for the best result is measured to be 3.11 μm. Optimal machine parameters for wire bonding are determined to be 70 mW power, 20 gf force, and 20 ms for the pitch adapter and 60 mW power, 20 gf force, and 20 ms for the silicon strip sensors; these parameters provide a pull force of (10.92±0.72) gf. With these settings, 75% of the pitch adapters and 25% of the strip sensors experience the neck - broken type of break. [ABSTRACT FROM AUTHOR]

Abstract: The ALPHA collaboration, based at CERN, has recently succeeded in confining cold antihydrogen atoms in a magnetic minimum neutral atom trap and has performed the first study of a resonant transition of the anti-atoms. The ALPHA apparatus will be described herein, with emphasis on the structural aspects, diagnostic methods and techniques that have enabled antihydrogen trapping and experimentation to be achieved. [Copyright &y& Elsevier]

Abstract: B-factories like the KEKB in Tsukuba, Japan, operate at relatively low energies and thus require detectors with very low material budget in order to minimize multiple scattering. On the other hand, front-end chips with short shaping time like the APV25 have to be placed as close to the sensor strips as possible to reduce the capacitive load, which mainly determines the noise figure. In order to achieve both – minimal material budget and low noise – we developed a readout scheme for double-sided silicon detectors, where the APV25 chips are placed on a flexible circuit, which is glued onto the top side of the sensor. The bottom-side strips are connected by two flexible circuits, which are bent around the edge of the sensor. This so-called “Origami” design will be utilized to build the Silicon Vertex Detector of the Belle II experiment, which will consist of four layers made from ladders with up to five double-sided silicon strip sensors in a row. Each ladder will be supported by two ribs made of a carbon fiber and Airex foam core sandwich. The heat dissipated by the front-end chips will be removed by a highly efficient two-phase CO2 system. Thanks to the Origami concept, all APV25 chips are aligned in a row and thus can be cooled by a single thin cooling pipe per ladder. We present the concept and the assembly procedure of the Origami chip-on-sensor modules. [Copyright &y& Elsevier]

Abstract: The Belle experiment at the KEKB electron/positron collider in Tsukuba (Japan) was successfully running for more than ten years. A major update of the machine to SuperKEKB is now foreseen until 2015, aiming a peak luminosity which is 40 times the peak value of the previous system. This also requires a redesign of the Belle detector (leading to Belle II) and especially its Silicon Vertex Detector (SVD), which surrounds the beam pipe. The future Belle II SVD will consist of four layers of double-sided silicon strip sensors based on 6in. silicon wafers. Three of the four layers will be equipped with trapezoidal sensors in the slanted forward region. Moreover, two inner layers with pixel detectors based on DEPFET technology will complement the SVD as innermost detector. Since the KEKB-factory operates at relatively low energy, material inside the active volume has to be minimized in order to reduce multiple scattering. This can be achieved by arranging the sensors in the so-called “Origami chip-on-sensor concept”, and a very light-weight mechanical support structure made from carbon fiber reinforced Airex foam. Moreover, cooling for the front-end chips will ensure high efficiency at minimum material budget. In this paper, an overview of the future Belle II SVD design will be given, covering the silicon sensors, the readout electronics and the mechanics. A strong emphasis will be given to our R&D work on double-sided sensors where different p-stop layouts for the n-side of the detectors were compared. Moreover, this paper gives updated numbers for the mechanical dimensions of the ladders and their radii. [Copyright &y& Elsevier]

The ALPHA project is an international collaboration, based at CERN, with the experimental goal of performing precision spectroscopic measurements on antihydrogen. As part of this endeavor, the ALPHA experiment includes a silicon tracking detector. This detector consists of a three-layer array of silicon modules surrounding the antihydrogen trapping region of the ALPHA apparatus. Using this device, the antihydrogen annihilation position can be determined with a spatial resolution of better than 5 mm. Knowledge of the annihilation distribution was a critical component in the recently successful antihydrogen trapping effort. This paper will describe the methods used to reconstruct annihilation events in the ALPHA detector. Particular attention will be given to the description of the background rejection criteria. [ABSTRACT FROM AUTHOR]

Abstract: After 10 years of successful operation, the Belle experiment at KEK (Tsukuba, Japan) will be completed in 2010. Thereafter, a major upgrade of the KEK-B machine is foreseen until 2014, aiming at a final luminosity of 8×1035 cm−2 s−1, which is about 40 times higher than the present peak value. Consequently, also the Belle experiment needs to be changed and the Silicon Vertex Detector (SVD) in particular will be completely replaced as it already operates close to its limits in the present system. The future SVD (a.k.a. SuperSVD) will consist of four layers of double-sided silicon strip detectors like the present one, but at larger radii, because it will be complemented by a two-layer pixel detector as the innermost sensing device. The SuperSVD will be entirely composed of silicon sensors made from 6in. wafers read out by APV25 front-end chips that were originally developed for the CMS experiment at the LHC. Several years of R&D effort led to innovations such as the Origami chip-on-sensor concept and readout electronics with hit time finding which were successfully demonstrated on prototypes. These features will be included in the final system which is presently being designed. This paper will give an overview of the SuperSVD and present results from prototype tests ranging from detector modules to back-end electronics. [ABSTRACT FROM AUTHOR]

The Belle II experiment at the SuperKEKB asymmetric e + e − collider in Japan will operate at a luminosity approximately 50 times larger than its predecessor (Belle). At its heart lies a six-layer vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is time-dependent CP violation asymmetry, which hinges on a precise charged-track vertex determination. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision three dimensional coordinate measurements of the jigs used in assembly as well as of the final SVD modules. [ABSTRACT FROM AUTHOR]

Abstract: The CDF Run II silicon detector is a 722,432 channel system designed to perform precision tracking and vertex measurements. After a challenging commissioning period, this detector is now used in regular data taking, recording 1fb−1 of data over the last four years. A summary of the problems encountered during commissioning is given as well as experiences of maintaining and operating such a large, complex detector. A comment on the longevity of the silicon detector is also given. [Copyright &y& Elsevier]

Abstract: The silicon vertex detector (SVD2) of the Belle experiment at KEK (Tsukuba, Japan) is currently close to its limits in terms of the occupancy of the innermost layer and the readout dead time. In order to cope with further increase in luminosity, different levels of upgrades are proposed: small improvements are possible in the short term by tuning the current system at the cost of signal-to-noise and crosstalk. In 2007, the two inner layers of the SVD2 will be replaced by similar detectors with faster readout electronics (SVD2.5) and in the long term, a major upgrade of the full silicon vertex detector (SVD3) is envisaged for the KEK Super B Factory. These upgrade scenarios will be discussed in detail from the hardware point of view along with the options under study. [Copyright &y& Elsevier]

Abstract: The PHENIX experiment at the Relativistic Heavy Ion Collider studies strongly interacting matter in nucleus–nucleus, polarized proton–proton and proton (deuterium)–nucleus collisions. Its prime fields of research are the exploration of hot and dense nuclear matter, studies of the gluon spin composition of the nucleon, and investigations of parton structures in nuclei. The experiment is being upgraded with a silicon vertex detector that will substantially enhance the physics capabilities of its central arm spectrometers. The silicon vertex detector consists of a four-layer barrel, built from two internal layers of pixel detectors and two external layers of projective “strip-pixel” detectors which complement the central electron spectrometer arms of PHENIX. In this paper, the physics motivation of the upgrade and the concept of the new detector are outlined. The status of new developments and the beginning production of the silicon detectors are presented. [Copyright &y& Elsevier]

Abstract: A new silicon vertex detector for the Belle experiment has been in operation at the high-luminosity asymmetric energy electron–positron collider KEKB since October 2003. It provides a larger polar angle acceptance, a better vertex resolution and a higher radiation tolerance than the previous one. The obtained performances indicate that the SVD2 works reliably, in very good agreement with expectations. [Copyright &y& Elsevier]

Abstract: The H1 experiment at HERA is equipped with a silicon vertex detector, comprising a barrel part and two endcaps with disks. The barrel part uses double sided, DC coupled strip sensors, whereas the endcap parts use two types of wedge-shaped sensors, both single sided and AC coupled: -sensors have strips parallel to one edge of the sensor, r-sensors have circular strips. Additional pad detectors provide fast triggering signals in the backward part. [Copyright &y& Elsevier]

Abstract: The Collider Detector of Fermilab RunII (CDFII) silicon detector consists of 8 layers of double-sided silicon micro-strip sensors and a total of 722,432 readout channels, making it one of the largest silicon detector currently in use by a HEP experiment. The detector has been commissioned since 2002, and now we are consistently taking good data with 85% of the detector. By 2009, we expect to accumulate 4– of luminosity. With no upgrade planned, studies of lifetime and radiation hardness of the detectors are discussed. As the luminosity delivered by the Tevatron has increased, measurable effects of radiation damage have been observed. Studies of charge collection and noise versus applied bias voltage at several different integrated luminosities are shown. These results and their impact on the lifetime of the detector are discussed. [Copyright &y& Elsevier]

In autumn 2003, data taking with the new silicon vertex detector SVD2.0 in Belle started at the KEK-B energy-asymmetric e+e- collider in Tsukuba, Japan. The detector works as expected, however, it was decided to produce replacement ladders for the inner two layers of the vertex detector which are most exposed to the high radiation dose from the beam. The new ladders do not merely reproduce the existing design but include some significant improvements. The readout electronics is implemented on a hybrid board with a new heat transfer scheme in order to dissipate the heat produced in the front-end readout chip. The flex circuits that connect the double-sided silicon sensors (DSSDs) with the hybrid boards were redesigned using a 2-layer technique which improved the production quality and lowered their costs significantly. Production kind testing will be finished in summer 2005 and will provide Belle with spare ladders as well as new expertise for possible future projects for example the high luminosity B-factory. [ABSTRACT FROM AUTHOR]

Abstract: Carbon fiber support structures have become common elements of detector designs for high energy physics experiments. Carbon fiber has many mechanical advantages but it is also characterized by high conductivity, particularly at high frequency, with associated design issues. This paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements. Tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10–100MHz. The general principles of grounding configurations involving carbon fiber structures will be discussed. To illustrate the design requirements, measurements performed with a silicon detector on a carbon fiber support structure at small radius are presented. A grounding scheme employing copper–kapton mesh circuits is described and shown to provide adequate and robust detector performance. [Copyright &y& Elsevier]

Abstract: The PHENIX experiment is planning to make a new silicon vertex tracker (VTX) for a detector upgrade to enhance the capability of detecting open heavy flavors. In this paper, the conceptual design of VTX and physics programs with VTX are introduced and then current R&D activities in PHENIX are presented. [Copyright &y& Elsevier]

Abstract: The H1 experiment at HERA is equipped with a silicon vertex detector, comprising a barrel part and two endcaps with disks. The barrel part uses double-sided, DC-coupled strip sensors, whereas the endcap parts use two types of wedge-shaped sensors, both single-sided and AC-coupled: sensors have strips parallel to one edge of the sensor, r sensors have circular strips. Additional pad detectors provide fast triggering signals in the backward part. [Copyright &y& Elsevier]

Abstract: The Belle Silicon Vertex Detector (SVD) was designed to measure B meson decay positions precisely for studies of time-dependent CP violation. Although the first version of SVD (SVD1) worked for 4years from 1999 with excellent performance, its insufficient radiation hardness drove us to build a second generation SVD (SVD2). The SVD2 was installed in Belle in the summer of 2003 and has been working well. The strip yield is estimated to be more than 95%. The signal-to-noise ratios are obtained to be 18–36, depending on detector ladders. The intrinsic spatial resolutions are obtained to be and for - and z-sides, where z-side measures positions along the beam direction and side is used for the azimuthal angle measurement. In this letter, an overview and performance results are provided for both generations of the Belle SVD. [Copyright &y& Elsevier]

Abstract: The Silicon Vertex Detector (SVD) of the Belle experiment is one of the main components for the investigation of time-dependent CP-asymmetries at the B-factory at KEK. The first version of this device (SVD1) was operated for 4 years starting in 1999 with excellent performance. However, its major limitations necessitated the design of a new detector (SVD2) which was installed in the summer shutdown of 2003. The improvements of the hardware and first results on the performance under real beam conditions are presented. [Copyright &y& Elsevier]

Abstract: The proper-time resolution function for the measurement of the time evolution of B mesons with the Belle detector at KEKB is studied in detail. The obtained resolution function is applied to the measurement of B meson lifetimes, the oscillation frequency and time-dependent CP asymmetries. [Copyright &y& Elsevier]

Fermilab plans to deliver 5–15 fb−1 of integrated luminosity to the CDF and D0 experiments. The current inner silicon detectors at CDF (SVXIIa and L00) will not tolerate the radiation dose associated with high-luminosity running and will need to be replaced. A new readout chip (SVX4) has been designed in radiation-hard 0.25 μm, CMOS technology. Single-sided sensors are arranged in a compact structure, called a stave, with integrated readout and cooling systems. This paper describes the general design of the Run IIb system, testing results of prototype electrical components (staves), and prototype silicon sensor performance before and after irradiation. [Copyright &y& Elsevier]

The PHENIX experiment at the Relativistic Heavy Ion Collider has completed its baseline instrumentation for the start of the presently ongoing third physics run. In the next few years, PHENIX will focus on high-statistics measurements in this configuration. It is expected that the collider will reach full luminosity with heavy ion and polarized proton beams by the year 2006. An upgraded collider is intended for the second half of the decade, with a luminosity increase to about 20–40 times the design value of 8×1026 cm−2 s−1 for Au+Au, and 2×1032 cm−2 s−1 for polarized proton beams. The collision energies of √ of sNN=200GeV will increase to sNN=200 GeV will increase to √ of sNN=500 GeV for proton beams. The PHENIX collaboration plans to upgrade its experiment to exploit with an enhanced detector new physics then in reach. A silicon vertex detector comprising pixel and novel microstrip sensors in a new vertex spectrometer is the main new sub-system discussed. This paper overviews the physics motivation and the detector concept chosen, and explains the directions of the beginning research and development effort. [Copyright &y& Elsevier]

The installation of the new Belle Silicon Vertex Detector SVD 2 during the summer of 2003 will bring some substantial improvements in the tracking and triggering capabilities of the Belle detector (Nucl. Instr. Meth. A 479 (2002) 117). A trigger part is included in the front-end readout electronics and a new hardware trigger Level 1.5 is introduced. Both improvements are essential in dealing with the increasing peak luminosities of the KEKB machine. [Copyright &y& Elsevier]

Since 1997, the H1 detector at the HERA collider at DESY, Hamburg has been equipped with a two layer silicon vertex detector (CST). The CST uses double sided, double metal layer sensors; it is read out with a specifically designed analog pipeline chip (APC), the signals are transmitted optically. The whole detector has a thickness of only 0.40 g/cm, corresponding to 1.4%X0. An asymptotic impact parameter resolution of 57 μm has been achieved.In 2001, the detector was redesigned for the HERA luminosity upgrade. It has been equipped with a new version of the readout chip APC that has been produced in radiation hard DMILL technology. [Copyright &y& Elsevier]

The Belle Silicon Vertex Detector (SVD) started working from June 1999 at the KEK B-factory experiment. The main purpose of the SVD is to make precise measurements of the B decay vertex position, which are essential for the observation of CP asymmetries. Excellent vertex resolution and a good detection efficiency are required for the SVD. In the present paper, the performance of Belle SVD is reviewed. The upgrade plan for the SVD2, which is under construction and will be installed in summer 2002, is also presented. [Copyright &y& Elsevier]

The Analog Pipeline Chip (APC) is a low noise, low power readout chip for silicon micro strip detectors with 128 channels containing an analog pipeline of 32 buffers depth. The chip has been designed for operation at HERA with a power dissipation of 300–400 μW per channel and has been used also in several other particle physics experiments. In this paper, we describe the development of a radiation hard version of this chip that will be used in the H1 vertex detector for operation at the luminosity upgraded HERA machine. A 128 channel prototyping chip with several amplifier variations has been designed in the radiation hard DMILL technology and measured. The results of various parameter variations are presented in this paper. Based on this, the design choice for the final production version of the APC128-DMILL has been made. [Copyright &y& Elsevier]