D. Hits

This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.

A novel device using single-crystal chemical vapour deposited diamond and resistive electrodes in the bulk forming a 3D diamond detector is presented. The electrodes of the device were fabricated with laser assisted phase change of diamond into a combination of diamond-like carbon, amorphous carbon and graphite. The connections to the electrodes of the device were made using a photo-lithographic process. The electrical and particle detection properties of the device were investigated. A prototype detector system consisting of the 3D device connected to a multi-channel readout was successfully tested with 120 GeV protons proving the feasibility of the 3D diamond detector concept for particle tracking applications for the first time.

Beam test results of the radiation tolerance study of chemical vapour deposition (CVD) diamond against different particle species and energies is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition functionality of poly-crystalline CVD diamond 3D devices was demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high luminosity experiments.

Pseudomorphic Si1−yCy alloys on silicon (100) were grown by molecular beam epitaxy using a single effusion source of silicon contained in a graphite crucible, producing carbon concentrations of y=0.008. The behavior of carbon incorporation using this source was studied as a function of growth temperature using x-ray diffraction and infrared spectroscopy, and was compared to previous studies, where Si1−yCy was grown from separate silicon and graphite sources. An increased energy barrier for the surface diffusion of carbon was observed using the single silicon–graphite source. An infrared absorption mode near 725 cm−1, observed for growth temperatures up to 700 °C, was attributed to a transitional phase between the loss of substitutional carbon and the formation of silicon carbide precipitates.

With the commissioning of the LHC in 2010 and upgrades expected in 2015, ATLAS and CMS are planning to upgrade their innermost tracking layers with radiation hard technologies. Chemical Vapor Deposition diamond has been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. This material is now being considered as a sensor material for use very close to the interaction region where the most extreme radiation conditions exist. Recently the RD42 collaboration constructed, irradiated and tested polycrystalline and single-crystal chemical vapor deposition diamond sensors to the highest fluences expected at the super-LHC. We present beam test results of chemical vapor deposition diamond up to fluences of 1.8×1016 protons/cm2 illustrating that both polycrystalline and single-crystal chemical vapor deposition diamonds follow a single damage curve. We also present beam test results of irradiated complete diamond pixel modules.

Metastable Si1 − x − yGexCy alloys were grown by molecular beam epitaxy on (100) Si substrates. Solid elemental sources were used for the Si and Ge beams, and a resistively heated graphite filament was used for the C beam. Up to 3 at% of C was incorporated in the alloy layers. Optical transmission measurements showed that the absorption edge of thick layers increased to higher energies with increasing C fraction, and revealed the presence of SiC and GeC vibrational modes in the infrared. At low temperatures, the alloys showed significant photoluminescence. The bandgap energies of thick layers increased linearly with the C fraction and followed a linear dependence of the bandgap on composition. Measurements of the valence band density of states using X-ray photoelectron spectroscopy indicated that the valence band energy maximum increased with the C fraction relative to that of SiGe alloys of similar composition. Our results indicated that SiGeC alloys are promising materials for Si-based heterostructure devices.

The structural, optical, and electronic properties of an insulating material prepared by the thermal oxidation of AlN thin films on Si have been studied by a number of different experimental techniques. The thermal oxidation at 1100 °C of reactively sputtered AlN films on Si wafers was found to result in the formation of an oxide with a relative Al to O concentration near Al2O3 with small amounts of incorporated N. The structure of the AlO:N oxide could be varied between amorphous and polycrystalline, depending on the preparation conditions, and the oxide surface was found to be approximately three time smoother than the as-sputtered AlN films. Metal–oxide–silicon capacitors had an oxide charge density of about 1011 cm−2, capacitance–voltage characteristics similar to pure SiO2, and a dielectric constant of 12.4. Infrared measurements yielded a refractive index of 3.9. These results indicate that thermally oxidized AlN films show promise as insulating structures for many integrated circuit applications, particularly for the case of III–V and group III–nitride based semiconductors.

The observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of √s = 7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9  fb^(-1), respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is 1.26^(+0.31)_(−0.26).

Abstract We have measured the radiation tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after irradiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm −2 and protons cm −2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irradiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irradiation energy and the irradiation fluence. We find for each irradiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradiated with 24 GeV protons to be and the damage constant for diamond irradiated with 800 MeV protons to be . Moreover, we observe the pulse height decreases with fluence for poly-crystalline CVD material and within statistical errors does not change with fluence for single-crystalline CVD material for both 24 GeV proton irradiation and 800 MeV proton irradiation. Finally, we have measured the uniformity of each sample as a function of fluence and observed that for poly-crystalline CVD diamond the samples become more uniform with fluence while for single-crystalline CVD diamond the uniformity does not change with fluence.

We measured the radiation tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 μm pitch strip detector fabricated on each diamond sample before and after irradiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8±0.9) × 1015 protons/cm2, (1.43±0.14) × 1016 neutrons/cm2, and (6.5±1.4) × 1014 pions/cm2, respectively. By observing the charge induced due to the separation of electron-hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irradiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62±0.07(stat)±0.16(syst)× 10-18 cm2/(p μm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65±0.13(stat)±0.18(syst)× 10-18 cm2/(n μm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0±0.2(stat)±0.5(syst)× 10-18 cm2/(π μm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irradiation and 800 MeV proton irradiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irradiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve.

The present CMS pixel Read Out Chip (ROC) was designed for operation at a bunch spacing of 25 ns and to be efficient up to the nominal instantaneous luminosity of 1034 cm−2 s−1. Based on the excellent LHC performance to date and the upgrade plans for the accelerators, it is anticipated that the instantaneous luminosity could reach 2×1034 cm−2 s−1 before the Long Shutdown 2 (LS2) in 2018, and well above this by the LS3 in 2022. That is why a new ROC has been designed and why a completely new pixel detector will be built with a planned installation in CMS during an extended winter shutdown in 2016/17. The ROC for the upgraded pixel detector is an evolution of the present architecture. It will be manufactured in the same 250 nm CMOS process. The core of the architecture is maintained, with enhancement in performance in three main areas: readout protocol, reduced data loss and enhanced analog performance. The main features of the new CMS pixel ROC are presented together with measured performance of the chip.

Diamond devices have now become ubiquitous in the LHC experiments, finding applications in beam background monitoring and luminosity measuring systems. This sensor material is now maturing to the point that the large pads in existing diamond detectors are being replaced by highly granular tracking devices, in both pixel and strip configurations, for detector systems that will be used in Run II at the LHC and beyond. The RD42 collaboration has continued to seek out additional diamond manufacturers and quantify the limits of the radiation tolerance of this material. The ATLAS experiment has recently installed, and is now commissioning a fully-fledged pixel tracking detector system based on diamond sensors. Finally, RD42 has recently demonstrated the viability of 3D biased diamond sensors that can be operated at very low voltages with full charge collection. These proceedings describe all of these advances.

The thermal stability of molecular beam epitaxy grown Si1−x−yGexCy/Si heterostructures (0⩽x<0.30, y∼0.008) was studied using infrared absorption spectroscopy. The local vibrational mode of C in Si and Si1−x−yGex was used to quantify the loss of C atoms from substitutional sites with high temperature annealing. The activation energy (Ea=4.9 eV) for the loss of substitutional C achieved a maximum for the strain compensated alloy (x∼0.1). An additional increase of Ge content resulted in a rapid decrease in Ea, which was found to be 3.4 eV for x∼0.27. The nonmonotonic behavior of Ea on Ge content is explained by the effect of the interface strain between the epitaxial layer and Si substrate.

Detectors based on Chemical Vapor Deposition (CVD) diamond have been used extensively and successfully in beam conditions/beam loss monitors as the innermost detectors in the highest radiation areas of Large Hadron Collider (LHC) experiments. The startup of the LHC in 2015 brought a new milestone where the first polycrystalline CVD (pCVD) diamond pixel modules were installed in an LHC experiment and successfully began operation. The RD42 collaboration at CERN is leading the effort to develop polycrystalline CVD diamond as a material for tracking detectors operating in extreme radiation environments. The status of the RD42 project with emphasis on recent beam test results is presented.

In sight of the luminosity increase of the High Luminosity-LHC (HL-LHC), most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades for their innermost layers in the next 5–10 years. These upgrades will require more radiation tolerant technologies than exist today. Usage of Chemical Vapor Deposition (CVD) diamond as detector material is one of the potentially interesting technologies for the upgrade. CVD diamond has been used extensively in the beam condition monitors of BaBar, Belle, CDF and all LHC experiments. Measurements of the radiation tolerance of the highest quality polycrystalline CVD material for a range of proton energies, pions and neutrons obtained with this material are presented. In addition, new results on the evolution of various semiconductor parameters as a function of the dose rate are described.

In the present study, results towards the development of a 3D diamond sensor are presented. Conductive channels are produced inside the sensor bulk using a femtosecond laser. This electrode geometry allows full charge collection even for low quality diamond sensors. Results from testbeam show that charge is collected by these electrodes. In order to understand the channel growth parameters, with the goal of producing low resistivity channels, the conductive channels produced with a different laser setup are evaluated by Raman spectroscopy.

We demonstrate the application of two-photon absorption transient current technique to wide bandgap semiconductors. We utilize it to probe charge transport properties of single-crystal Chemical Vapor Deposition (scCVD) diamond. The charge carriers, inside the scCVD diamond sample, are excited by a femtosecond laser through simultaneous absorption of two photons. Due to the nature of two-photon absorption, the generation of charge carriers is confined in space (3-D) around the focal point of the laser. Such localized charge injection allows to probe the charge transport properties of the semiconductor bulk with a fine-grained 3-D resolution. Exploiting spatial confinement of the generated charge, the electrical field of the diamond bulk was mapped at different depths and compared to an X-ray diffraction topograph of the sample. Measurements utilizing this method provide a unique way of exploring spatial variations of charge transport properties in transparent wide-bandgap semiconductors.

We describe results from a beam test of a telescope consisting of three planes of single-crystal, diamond pixel detectors. This telescope is a prototype for a small-angle luminosity monitor, the Pixel Luminosity Telescope (PLT), for CMS. We recorded the pixel addresses and pulse heights of all pixels over threshold as well as the fast-or signals from all three telescope planes. We present results on the telescope performance including occupancies, pulse heights, fast-or efficiencies and particle tracking. These results show that the PLT design meets all required specifications.

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.

We have measured the radiation tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 µm pitch strip detector fabricated on each diamond sample before and after irradiation.We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV) and a third group of samples with 200 MeV pions, in steps, to (8.8 ± 0.9) × 10 15 protons/cm 2 , (1.43 ± 0.14) × 10 16 neutrons/cm 2 and (6.5 ± 0.5) × 10 14 pions/cm 2 respectively.By observing the charge induced due to the separation of electron-hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irradiation fluence, we conclude all data sets can be described by a first order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons and 200 MeV pions.We find the damage constant for diamond irradiated with 70 MeV protons to be 1.61 ± 0.07 (stat) ± 0.15 (syst) × 10 -18 cm 2 /(p µm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65 ± 0.13 (stat) ± 0.16 (syst) × 10 -18 cm 2 /(n µm) and the damage constant for diamond irradiated with 200 MeV pions to be 2.0 ± 0.2 (stat) ± 0.5 (syst) × 10 -18 cm 2 /(π µm).The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irradiation and 800 MeV proton irradiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond.We find 70 MeV protons are 2.60 ± 0.27 times more damaging than 24 GeV protons, fast reactor neutrons are 4.27 ± 0.34 times more damaging than 24 GeV protons and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons.We also observe the measured data can be described by a universal damage curve for all proton, neutron and pion irradiations we have performed of Chemical Vapor Deposition diamond.Finally, we confirm the FWHM/MP ratio of the signal spectrum, a measure of the spatial uniformity of the collected charge, decreases with fluence for polycrystalline Chemical Vapor Deposition diamond and this effect can also be described by a universal curve.

The effects of alloying C with Ge and Si and varying the C/Ge ratio during the growth of very thin layers of the ternary alloy SiGeC grown on Si (100) substrates and the resulting strain modification on self-assembled and self-organized quantum dots are examined. During coherent islanded growth, where dislocations are not formed yet to relieve the strain, higher strain energy produced by greater lattice mismatch acts to reduce the island size, increase the density of islands, and significantly narrow the distribution of island sizes to nearly uniformly sized quantum dots. Strain energy can also control the critical thickness for dislocation generation within the three-dimensional islands, which then limits the maximum height which coherent islands can achieve. After the islands relax by misfit dislocations, the island sizes increase and the island size distribution becomes broader with the increase of misfit and strain. The optimal growth for a high density of uniform coherent islands occurred for the Si0.49Ge0.48C0.03 alloy composition grown on (100) Si, at a growth temperature of 600 °C, with an average thickness of 5 nm, resulting in a narrow size distribution (about 42 nm diameter) and high density (about 2×1010 dots/cm2) of quantum dots.

Group IV semiconductor alloy systems offer promise as variable band gap alloys compatible with Si technology. Binary, ternary, and quaternary group IV alloys were grown by molecular beam epitaxy on Si substrates. The fundamental absorption edge was measured by Fourier transform infrared spectroscopy to obtain the optical band gap of the alloys, and the position of the fundamental absorption edge was observed to depend on the experimentally measured alloy composition. Our results indicate a variety of Si-rich group IV alloys with various band gaps are experimentally producible.

The Pixel Luminosity Telescope (PLT) system is an innovative luminosity monitor being developed as an early upgrade for the CMS detector at the LHC. An essential feature of the PLT is the use of single crystal diamond, grown by chemical vapor deposition, as the active sensor material. The radiation hardness of diamond, along with its lack of need for active cooling, are key to the design and functioning of the PLT. While diamond sensors have been used in several collider experiments, primarily for monitoring of beam conditions, these have mostly been based on poly-crystal diamonds. The PLT will be the first device to rely on the use of a single-crystal diamond and the first to use diamond pixel sensors. We will discuss the important role that a single-crystal diamond will play in the PLT operation. We will contrast single-crystal to poly-crystal diamond sensors, provide an overview of the PLT concept, and present results on its performance.

The Pixel Luminosity Telescope (PLT) is an innovative luminosity monitor which is planned as an upgrade for the CMS detector at the LHC. It uses pixelated single-crystal diamonds as the active sensor material bumpbonded to standard CMS pixel readout electronics. The PLT makes use of a presently unused feature of the pixel readout chip which was designed to provide a hit-over-threshold signal to a hardware trigger processor. This feature will produce a bunch crossing (25 ns) `hit' signal that can form the basis of luminosity information at the hardware level. We will report on the first successful use of this `Fast-Or' signal to self-trigger on beta particles from a source using a diamond pixel detector. Expected performance of the PLT based on Pythia simulations is also detailed.

The publisher regrets p 98,“The electrode yield, i.e. the fraction of electrodes produced with a continuous conducting path over the thickness of the diamondsample, was estimated by optical and electrical inspection and found to be9273%.”(Was“9270.3%”) p101, Figure 8 of the paper misses the legend, corrected figure: p103, Figure 13b) of the paper misses 3 blue bin entries (corner bins) of the four, only one entry is visible.

The centroid of neutral electron trap distribution in 80 Å SiO2 film after high-field electrical stress is determined using trap-filling measurements that can eliminate the contributions from trapped holes and interface trapped charges—complications that introduce ambiguity in previous studies. The centroid is found to be roughly half way between the midpoint of the oxide and the injecting electrode, implying an extremely nonuniform distribution. Such a highly nonuniform distribution is at odds with the assumption used in most oxide breakdown models. The impact of a highly nonuniform neutral trap distribution on thin oxide reliability projection could be important.

The planned upgrade of the LHC to the High-Luminosity-LHC will push the luminosity limits above the original design values. Since the current detectors will not be able to cope with this environment ATLAS and CMS are doing research to find more radiation tolerant technologies for their innermost tracking layers. Chemical Vapour Deposition (CVD) diamond is an excellent candidate for this purpose. Detectors out of this material are already established in the highest irradiation regimes for the beam condition monitors at LHC. The RD42 collaboration is leading an effort to use CVD diamonds also as sensor material for the future tracking detectors. The signal behaviour of highly irradiated diamonds is presented as well as the recent study of the signal dependence on incident particle flux. There is also a recent development towards 3D detectors and especially 3D detectors with a pixel readout based on diamond sensors.

Diamond is used as detector material in high energy physics experiments due to its inherent radiation tolerance. The RD42 collaboration has measured the radiation tolerance of chemical vapour deposition (CVD) diamond against proton, pion, and neutron irradiation. Results of this study are summarized in this article. The radiation tolerance of diamond detectors can be further enhanced by using a 3D electrode geometry. We present preliminary results of a poly-crystalline CVD (pCVD) diamond detector with a 3D electrode geometry after irradiation and compare to planar devices of roughly the same thickness.

Quantum dots of Si1−x−yGexCy alloys with high Ge contents were grown on Si(311) and Si(001) substrates by solid source molecular beam epitaxy and were measured by atomic force microscopy. The quantum dot layers had a nominal thickness (equivalent two-dimensional) of 4 nm. The smallest quantum dots occurred for the composition Si0.09Ge0.9C0.01 on Si (311), and had a 40 nm mean diameter, an 8 nm mean height, and a density of 3.3×1010 cm−2. Quantum dots on Si(001) were larger and had less regular spacing than quantum dots on Si(311) with the same composition. Carbon decreased both the mean size and spacing of SiGe quantum dots and the ratio of size deviation to mean diameter. The presence of small uniform quantum dots for particular compositions is attributed to a reduction in the surface migration of adatoms due to decreased atomic surface diffusivity. These results suggest that quantum dot organization is controlled by composition, substrate orientation, strain, and surface diffusion.

High voltage thyristors have been fabricated by direct wafer bonding. Thyristors were fabricated by joining anode and cathode wafers nominally designed for 6 kV operation. Wafer bonded 100 mm diameter thyristors with breakdown voltages exceeding 7 kV were successfully fabricated. Bonded transistors with forward voltage drops comparable to control devices showed lower switching loss possibly due to advantageous recombination at the bond interface. This is the first demonstration of large area bonded power devices with breakdown voltages exceeding 6 kV.

In this paper, we report on asymmetric SiC GTOs (gate turn-off thyristors), fabricated at Northrop Grumman with the assistance of Silicon Power Co. A module containing six 1 mm/spl times/1 mm GTOs connected in parallel has demonstrated 100 A of switching current capability. This is the highest current reported to date with GTOs designed for greater than 3 kV forward blocking voltage. GTOs fabricated from the same wafer have achieved a forward blocking voltage of 3.1 kV, which was the testing limit of the instrumentation. This represents a record high breakdown voltage for GTOs with a drift layer thickness of 30 /spl mu/m. These GTOs also demonstrated record low leakage currents of <5 /spl mu/A at the forward blocking voltage of 3.1 kV.

The temperature dependence of thermopower of isostructural molecular conductors [Ni(dddt)2]3(HSO4)2 and (ET)3(HSO4)2 has been investigated. Drastic difference in S(T) dependences is qualitatively explained on basis of tight binding band structure calculations. A peak at 25 K in [Ni(dddt)2]3(HSO4)2 was shown to be manifestation of metal to semimetal phase transition, and the abrupt decrease at 125 K in (ET)3(HSO4)2 is concerned with metal to insulator phase transition. Rather complex semimetal band structure was found in both cases.

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 three layers of pixel diamond detectors that are aligned precisely with respect to each other and the beam direction, utilizing simultaneously performed particle track position measurements. The PLT's single-crystal CVD diamonds are bump-bonded to the PSI46 pixel readout chip - the same readout chip used in the silicon pixel system in CMS. Single-crystal CVD diamond pixel detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. They are expected to withstand the radiation near the beam pipe over several years at full LHC luminosity with a modest loss of pulse height and no increase of leakage currents. In order to further characterize the applicability of diamond technology to charged particle tracking, the intrinsic spatial resolution of single-crystal CVD diamonds was measured using a high resolution beam telescope developed at the University of Zurich. We present the results of these studies.

At present most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades in the next 5-10 years for their innermost tracking layers as well as luminosity monitors to be able to take data as the luminosity increases and CERN moves toward the High Luminosity-LHC (HL-LHC). These upgrades will most likely require more radiation tolerant technologies than exist today. As a result this is one area of intense research, and Chemical Vapour Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of all LHC experiments. This talk describes the preliminary radiation tolerance measurements of the highest quality polycrystalline CVD material for a range of proton energies and neutrons obtained with this material with the goal of elucidating the issues that should be addressed for future diamond based detectors. The talk presents the evolution of various semiconductor parameters as a function of dose.

Abstract We measured the dielectric function of Ge1−yCy and Ge-rich Si1−x−yGexCy alloys from 1.6 to 5.2 eV using spectroscopic ellipsometry. These alloys were grown by molecular beam epitaxy at 600°C on (001) Si substrates. Analytic lineshapes fitted to numerically calculated derivatives of their dielectric functions determined the critical-point parameters of the E1, E1+Δ1, E0′, and E2 transitions. The critical-point energies of the Ge1−yCy alloys were found to be indistinguishable from those of bulk Ge. This indicates that the presence of C in these alloys has no detectable influence on the band structure. The amplitude of the ellipsometric spectra is much lower than for bulk Ge, which can be attributed to surface roughness and explained within the framework of the Kirchhoff theory of diffraction or using effective medium theory. The degree of surface roughness indicated by optical measurements was verified by atomic force microscopy.

Ge<SUB>1-y</SUB>C<SUB>y</SUB> alloys are meta-stable and challenging to produce due to the large disparity between the atomic sizes of Ge and C. However, this same disparity results in an alloy system that potentially spans a wide range of bandgaps, refraction indices, and lattice constants. As such, it has potential as a Si lattice matched material for use in Si based waveguides, detectors, modulators, and other devices. The performance of these devices, however, depends on the refractive indices, which are not well known in these alloys. We present the results of comprehensive measurements of refractive index, energy bandgap, and free carrier absorption versus doping level. In situ B and P doped 550 nm Ge<SUB>1-y</SUB>C<SUB>y</SUB> alloy films were grown on Si (100) substrates by molecular beam epitaxy. The infrared optical transmission spectra were measured at room temperature. The indices of refraction were obtained from the amplitude of the interference fringes at sub-bandgap photon energies. Hall effect measurements were employed to measure the carrier concentrations. The refractive index of our Ge- 1-y)C<SUB>y</SUB> alloys was nominally 4.01, and decreased with increasing B and P concentration.

3D pixel technology has been used successfully in the past with silicon detectors for tracking applications.Recently, a first prototype of the same 3D technology has been produced on a chemical vapour deposited single-crystal diamond sensor.This device has been subsequently tested in a beam test at CERN's SPS accelerator in a beam of 120 GeV protons.Details on the production and results of testbeam data are presented.

The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction and planned for installation during the next CMS opening, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in an array of sixteen telescopes each consisting of three layers of pixel diamond detectors. The PLT's single-crystal CVD diamonds are bump-bonded to the PSI46 pixel readout chip - the same readout chip used in the silicon pixel system in CMS. Final hardware and software components have been assembled at CERN. The performance with has been measured this year in beams at the CERN PS, as well as the test beam facility at Fermilab. With respect to charged particle tracking, we also measured the Lorentz angle in a magnetic field at the CERN SPS. We present the results of these studies for the final system.

We describe the results from a beam test of a telescope consisting of three planes of single-crystal, diamond pixel detectors.This telescope is a prototype for a proposed small-angle luminosity monitor, the Pixel Luminosity Telescope (PLT), for CMS.We recorded the pixel addresses and pulse heights of all pixels over threshold as well as the fast-or signals from all three telescope planes.We present results on the telescope performance including occupancies, pulse heights, fast-or efficiencies and particle tracking.These results show that the PLT design concept is sound and indicate that the project is ready to proceed with the next phase of carrying out a complete system test.

The status of material development of poly-crystalline chemical vapor deposition (CVD) diamond is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm$^2$ to 10 MHz/cm$^2$. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition the first beam test results from 3D detectors made with poly-crystalline CVD diamond are presented. Finally the first analysis of LHC data from the ATLAS Diamond Beam Monitor (DBM) which is based on pixelated poly-crystalline CVD diamond sensors bump-bonded to pixel readout electronics is shown.

The Beam Conditions Monitor (BCM) provides fast, relative measurements of particle fluxes for use in the safety systems of CMS. It uses a set of chemical vapor deposited (CVD) diamond diodes. Sudden, order of magnitude changes in the BCM readout issue non-maskable LHC beam aborts. Dangerous irradiation trends on longer timescales translate into automatic detector interlocks and injection inhibit. Operators in the LHC beam and CMS detector control room obtain and display real time (1 Hz) readout of flux measurements from the BCM subsystem. The beam radiation monitoring system also provides an independent measurement of the beam luminosity. The next generation luminosity detector, called the Pixel Luminosity Telescope (PLT), is based on pixelated monocrystalline diamond detectors. They provide a fast occupancy information and allow particle tracking near the interaction point to distinguish trajectories originating from the proton-proton collision point and those parallel to the beam pipe. We present the use case of diamond detectors for beam radiation monitoring in CMS and first measurements of 150 GeV/c ¿ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> particle tracks in three layers of pixelated diamond detectors. The PLT after installation in 2010 will be the largest utilization of diamond instrumentation in high energy physics.

Diamond is a material in use at many nuclear and high energy facilities due to its inherent radiation tolerance and ease of use. We have characterized detectors based on chemical vapor deposition (CVD) diamond before and after proton irradiation. We present preliminary results of the spatial resolution of unirradiated and irradiated CVD diamond strip sensors. In addition, we measured the pulse height versus particle rate of unirradiated and irradiated polycrystalline CVD (pCVD) diamond pad detectors up to a particle flux of $20\,\mathrm{MHz/cm^2}$ and a fluence up to $4 \times 10^{15}\,n/\mathrm{cm^2}$.

As a possible candidate for extremely radiation tolerant tracking devices we present a novel detector design - namely 3D detectors - based on poly-crystalline CVD diamond sensors with a pixel readout. The fabrication of recent 3D detectors as well their results in recent beam tests are presented. We measured the hit efficiency and signal response of two 3D diamond detectors with 50 × 50 μm cell sizes using pixel readout chip technologies currently used at CMS and ATLAS. In all runs, both devices attained efficiencies >98 % in a normal incident test beam of minimum ionising particles. The highest efficiency observed during the beam tests was 99.2 %.

We have measured the radiation tolerance of chemical vapor deposition (CVD) diamond against protons and neutrons.The relative radiation damage constant of 24 GeV protons, 800 MeV protons, 70 MeV protons, and fast reactor neutrons is presented.The results are used to combine the measured data into a universal damage curve for diamond material.

A laser-based two-photon absorption transient-current technique is discussed. In this method free charge carriers are excited in the focal point inside the material. We record the current response of electron and hole drift in an externally applied electric field. Charge collection efficiency, electric field distribution and trapping rates are extracted.

The radiation tolerance of chemical vapor deposition (CVD) diamond against different particle species and energies has been studied in beam tests and is presented.We also present beam test results on signal size as a function of incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm 2 to 20 MHz/cm 2 .The pulse height of the sensors was measured using readout electronics with a peaking time of 6 ns.In addition, the functionality of poly-crystalline CVD diamond 3D devices is demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high rate/high intensity experiments.

Bandgap tailoring and lattice-matching in SiGeC/Si heterostructures has potential for improving the performance and capabilities of Si based optoelectronics. Although remarkable progress in the molecular beam epitaxy (MBE) of SiGeC/Si heterostructures has been achieved, important questions concerning growth kinetics and thermal stability are still not fully understood. One major obstacle during MBE growth of these heterostructures may be the high surface diffusivity of carbon, which leads to small fractions of substitutional carbon at temperatures necessary for device quality epitaxial growth. We report on the surface kinetic properties of Si<SUB>0.992</SUB>C<SUB>0.008</SUB>/Si and thermal stability of strained Si<SUB>0.992</SUB>C<SUB>0.008</SUB>/Si and strain compensated Si<SUB>0.892</SUB>Ge<SUB>0.10</SUB>C<SUB>0.008</SUB>/Si alloys were shown to be more stable then the binary Si<SUB>0.992</SUB>C<SUB>0.008</SUB>/Si heterostructure alloys.

Summary form only given. The thermopower vs temperature dependence of molecular conductors (Ni(dddt)2)3(HS04)2 and (ET)3(HS04)2 have been investigated. Their crystal structures differ only by substituting of central C=C fragment for Ni atom. While both compounds possess similar temperature dependences of resistivity (metal-insulator transition at 25 K and 125 K respectively) , S(T) dependences demonstrate a drastic difference. A peak at 25 K in (Ni(dddt)2)3(HS04)2 was shown to be manifestation of metal to semimetal phase transition, and the abrupt decrease at 125 K in (ET)3(HS04)2 is concerned with metal to insulator phase transition. Tight binding band structure and Fermi surface for both compounds have been calculated. Semimetal band structure was found in both cases. Difference of thermopower behaviour is qualitatively explained on basis of band structure calculations.