Jean-Marie Brom

The result of a search at the LHC for heavy stable charged particles produced in pp collisions at $ \sqrt {s} = 7\;{\text{TeV}} $ is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb−1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398GeV/c 2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c 2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.

Hadronic event shapes have been measured in proton-proton collisions at sqrt(s)=7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.

A measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations.

The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 inverse femtobarns, were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

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.

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented.

To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034 cm−2 s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016 cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016 cm−2.For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150 mm (6”) wafers with an active thickness of 150 µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0 µm for non-irradiated samples, and 6.3 µm after irradiation to Φeq = 7.2 × 1015 cm−2.

ABSTRACTPurpose There is a strong preference for evidence-based child welfare services, however, there are few well-researched programs for families that struggle post-permanence. Following adoption or guardianship, some families experience significant challenges, struggle to find effective programs, and run the risk of family instability. This study described the process used to develop the Adoption and Guardianship Enhanced Support (AGES) intervention and explored: 1) the needs of families participating in the program and 2) how AGES worked with families to address those challenges.Methods This descriptive study utilized quantitative structured assessment data and qualitative data from case records to explore the needs of families and provide context for qualitative, in-depth interviews with families regarding their experiences with the AGES program, presented using thematic analysis.Results Pre-service structured assessments indicated multiple dimensions of parenting strain, with case record reviews and interviews with families providing a nuanced picture of multiple sources of strain, suggesting the project was reaching the intended audience. Record review and interviews demonstrated strong alignment between needs of families and the support provided by AGES workers. Intended analysis of quantitative post-assessment data was not possible, due to lower enrollment and higher staff turnover than expected, as well as study timeframes.Discussion and Conclusion The approach utilized by AGES workers, one that walked alongside families and provided flexible responses to identified needs, showed promise for adoptive and guardianship families. Replication and additional research are needed to assess the program with a larger sample and more rigorous methods.KEYWORDS: Post adoption and guardianship stabilityPermanencyIntervention researchPost-permanency servicesPilot study Disclosure statementNo potential conflict of interest was reported by the author(s).Correction StatementThis article has been corrected with minor changes. These changes do not impact the academic content of the article.Additional informationFundingThe work was supported by the Department of Health and Human Services, Administration for Children and Families, Children’s Bureau [90CO1122].

A set of CMS MicroStrip Gas Chambers (MSGC) was exposed to a high-intensity 3GeV/c pion beam at a CERN PS facility for a period of two weeks. The performance of the detectors is reported in terms of stability of efficiency and response to minimum ionising particles as well as to more heavily ionising fragments generated by nuclear interactions.

Gas gain variations as functions of time have been observed with microstrip gas chambers. They are attributed here to charging of the substrate surface between electrodes. Based upon the concept of quasi-electrostatic fields a rule of charge accumulation is derived. Gas conductance is studied in order to apply the rule to a surface exposed to gas. A relation between substrate resistivity and the rate of detected particles for stable gain operation is then obtained by means of this rule. A comparison with experimental results yields good agreement.

Abstract During the beam test of a tracker prototype for the Compact Muon Solenoid detector proposed for the LHC, the time response of the Microstrip Gas Chambers was studied using different gases and chamber gaps. The subsequent efficiency to identify the bunch crossing at LHC is discussed for several algorithms used in the off-line signal processing of the data.

Abstract A system of detector modules consisting of a large size Gas Electron Multiplier (GEM), coupled to Micro Strip Gas Counters (MSGC), has been exposed to a pion beam at the Paul Scherrer Institute Cyclotron facility. As part of a CMS tracker milestone, the aim of this test was to investigate the robustness of such detectors when exposed to experimental conditions close to what is expected at the Large Hadron Collider (LHC) of CERN. Eighteen detector modules have been operated at voltage settings corresponding to 98% detection efficiency for Minimum Ionizing Particles during a period of 5 weeks. Sparking rates and strip losses have been monitored throughout the exposure. An operation margin of at least a factor of three with respect to the required gas gain has been demonstrated.

Abstract Damages to MSGCs induced by discharges have been investigated. Optimization of electrode shapes and/or deposition of a protective coating allows the increase of the potential difference between anode and cathode, thus increasing the gain. For prototypes of MSGCs made at the Centre de Recherches Nucleaires, each step of the manufacturing processes was carefully controlled. Results are presented on the influence of cleaning processes on the surface resistance of glass substrates.

Abstract We have studied the performance of several Microstrip Gas Chamber (MSGC) prototypes made on standard Desag D263 boron implanted glass. The purpose of the implantation is to reduce the surface resistance. The long term stability of this implantation has been measured under applied bias voltage. Comparative tests have been carried out on prototypes made on implanted and unimplanted detectors under electron ( 90 Sr) and X-ray (8 keV) irradiation. The total dose was approximately 7 mC/cm.

A prototype of the barrel Tracking Detector of the Compact Muon Solenoid (CMS) experiment proposed for LHC was built and tested in a beam and in a magnetic field of up to 3 T. It contained six microstrip gas chambers, 25 cm long, and three double-sided silicon microstrip detectors, 12.5 cm long. We report some preliminary results on the performance of the chambers.

A small series production of detector modules made of MicroStrip Gas Counters (MSGC) and a Gas Electron Multiplier (GEM) foil has been exposed to a high-intensity hadron beam. We report about the reproductibility and stability of the detector responses and about the occurrence and consequences of discharges in the detector. The interdependence of the four voltage differences used in the detector has been studied by simulation and with X-ray measurements. Rate dependence of the signal amplitude is observed. The behaviour of the MSGC+GEM is compared to that of a state-of-the-art MSGC. Influence of various parameters on the detector response is investigated.

A search for massive resonances decaying to a Z boson and a photon is performed in events with a hadronically decaying Z boson candidate, separately in light-quark and b quark decay modes, identified using jet substructure and advanced b tagging techniques. Results are based on samples of proton-proton collisions collected with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The results of the search are combined with those of a similar search in the leptonic decay modes of the Z boson, based on the same data sets. Spin-0 resonances with various widths and with masses in a range between 0.2 and 3.0 TeV are considered. No significant excess is observed either in the individual analyses or the combination. The results are presented in terms of upper limits on the production cross section of such resonances and constitute the most stringent limits to date for a wide range of masses.

The inelastic hadronic cross section in proton-lead collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample, corresponding to an integrated luminosity of 12.6 +/- 0.4 inverse nanobarns, has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the measured number of proton-lead collisions with hadronic activity produced in the pseudorapidity ranges 3<abs(eta)<5 and/or -5<abs(eta)<-3, corrected for photon-induced contributions, experimental acceptance, and other instrumental effects. The inelastic cross section is measured to be sigma[inel,pPb]=2061 +/- 3 (stat) +/- 34 (syst) +/- 72 (lum) mb. Various Monte Carlo generators, commonly used in heavy ion and cosmic ray physics, are found to reproduce the data within uncertainties. The value of sigma[inel,pPb] is compatible with that expected from the proton-proton cross section at 5.02 TeV scaled up within a simple Glauber approach to account for multiple scatterings in the lead nucleus, indicating that further net nuclear corrections are small.

We present some test results of microstrip gas chambers with boro-silicate glass substrates, which were coated before the photolithographic processing. We compare various coatings: sputtered S8900 glass and three coatings made by industrial companies (SURMET, VITO and ICMC). The composition and electrical properties of the different materials are discussed. Gain, current and rate capability are compared with those obtained from identical uncoated glass substrates.

To investigate the effects of neutrons on MSGCs, the gain of several detectors was measured before and after irradiation with a flux of 106neutrons/cm2s in the CEA (Saclay) ISIS reactor facility. On one of these prototypes the induced activity was measured after the irradiation.

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.

Microstrip gas chambers made from high resistivity substrates are often plagued by gain losses. A model of surface charging coupled to precise electrostatic simulations, which reveal details of electric fields close to the substrate surface, suggests how stable gains can be achieved nevertheless. Measurements support these considerations.

The need to understand surface and space charging of microstrip gas chambers requires a study of transverse diffusion for inhomogeneous electric fields. A differential equation is deduced for the time dependence of the root-mean-square dispersion of the distribution of drifting charges. Its solution yields estimates of electron clouds approaching the anodes, and of ion clouds leaving them. Comparisons to measurements are presented.

A novel position-sensitive micro-pattern gas detector called Sand-Glass is introduced. It has been manufactured using printed circuit board technique and its structure is based on two thin kapton foils joined together. The foils are copper-clad on both sides with the strip electrodes structure engraved on either side, and with a very dense perforation in the form of a conically shaped hole pattern etched through both foils, which forms the Sand-Glass shape. The two foils are in electrical contact; the outer faces form cathodes, and the inner layer becomes an anode. Due to the electric field symmetry, electrons from avalanches are collected on the central electrode of the Sand-Glass holes. This geometry may allow 2D readout in the single gas amplification structure. Preliminary results of the SGG detector prototype tests are reported.

We report on the performance of Micro-Gap Chambers is manufactured at Strasbourg. We present measurements of gain as a function of various operating parameters, such as high voltages and various gas mixtures. With the optimal mixture of Ne–DME (70–30%), a cathode voltage of −500 V and a drift voltage of −2900 V, a gain of ∼3000 is achieved. Performance of Micro-Gap Chambers is compared to that of Micro-Strip Gas Chambers.

The aim of this work was to quantify the influence of radiation-induced substrate defects on microstrip gas chamber (MSGC) gain behaviour. The first part of this paper focuses on radiation effects on a typical MSGC substrate: Desag D263 glass. Defect generation was studied for Desag D263 with pure silica (Suprasil 1) as a reference. We studied the evolution of defect concentration with respect to accumulated doses up to 480 kGy. Annealing studies of defects in Desag D263 were also performed. In the second part, the radiation sensitivity of Desag D263 glass has been linked to the behaviour of the detector under irradiation. Comparative gain measurements were taken before and after substrate irradiation at 10 and 80 kGy the minimal dose received during LHC operation and the dose for which defect density is maximum (respectively).

Charged particle multiplicity distributions from e{sup +}e{sup {minus}} annihilations at 29 GeV have been analyzed in selected rapidity and azimuthal angle intervals. The data were taken with the High Resolution Spectrometer at PEP. The factorial moments of the multiplicity distributions increase as the rapidity interval is decreased, the so-called intermittency phenomenon. These direct measurements of the moments agree with values derived from negative binomial fits to our multiplicity distributions in various central rapidity windows. The factorial moments are also given for the distribution in azimuthal angle around the beam direction and for the two-dimensional distribution in rapidity and azimuthal angle around the jet directions.

This paper reports the electroweak asymmetry in the reaction e/sup +/e/sup -/ ..-->.. tau/sup +/tau/sup -/ at 29 GeV. The results came from data taken with the High Resolution Spectrometer at PEP corresponding to an integrated luminosity of 256 pb/sup -1/. The 7372 observed events give A/sub tau tau/ = -(4.4 +- 1.4 +- 0.5)%. Events selected in the central region of the detector measure a total cross section of R/sub tau tau/ = 1.06 +- 0.02 +- 0.04. 5 refs., 1 fig.

We report on a search for the decay mode D/sup *//sup 0/(2007) ..-->.. D/sup +/..pi../sup -/ using the High Resolution Spectrometer at PEP. Although this decay is kinematically forbidden for the central mass value, it can occur through the natural width of the D/sup *//sup 0/. The D/sup +/ was reconstructed in the K/sup -/..pi../sup +/..pi../sup +/ decay mode. The mass difference distribution (K/sup -/..pi../sup +/..pi../sup +/..pi../sup +/) - (K/sup -/..pi../sup +/..pi../sup -/), which shows no threshold enhancement, leads to a preliminary upper limit on the branching ratio of B/sub r/(D/sup *//sup 0/ ..-->.. D/sup +/..pi../sup -/) < 15% at 90% CL. This, in turn, corresponds to an upper limit on the D/sup *//sup 0/ width of 1.5 MeV/c/sup 2/ at 90% CL. 4 refs., 3 figs.

Results from the NA36 experiment obtained with the /sup 32/S beam at the CERN SPS during the 1987 run are presented. Production of lambda particles by proton and /sup 32/S beams was studied. 8 figs.