Robert M Brown

We report an experimental determination of the cross section for e+e− → hadrons from a scan around the Z0 pole. On the basis of 4350 hadronic events collected over seven energy points between 89.26 GeV and 93.26 GeV we obtain a mass of mz=91.01±0.05±0.05 GeV, and a total decay width of Γz=2.60±0.13 GeV. In the context of the standard model t these results imply 3.1 ± 0.4 neutrino generations.

First measurements of the mass and width of the Z0 performed at the newly commissioned LEP Collider by the DELPHI Collaboration are presented. The measuements are derived from the study of multihadronic final states produced in e+e− annihilations at several energies around the Z0 mass. The values found for the mass and width are M(Z0)=91.06±0.09 (stat) ±0.045 (syst.) GeV and Γ(Z0)=2.42±0.21 (stat.) GeV respectively, froma three-parameter fit to the line shape. A two-parameter fit in the framework of the standard model yields for the number of light neutrino species Nν=2.4±0.4 (stat.) ±0.5 (syst.).

We present measurements of global event shape distributions in the hadronic decays of theZ 0. The data sample, corresponding to an integrated luminosity of about 1.3 pb−1, was collected with the OPAL detector at LEP. Most of the experimental distributions we present are unfolded for the finite acceptance and resolution of the OPAL detector. Through comparison with our unfolded data, we tune the parameter values of several Monte Carlo computer programs which simulate perturbative QCD and the hadronization of partons. Jetset version 7.2, Herwig version 3.4 and Ariadne version 3.1 all provide good descriptions of the experimental distributions. They in addition describe lower energy data with the parameter values adjusted at theZ 0 energy. A complete second order matrix element Monte Carlo program with a modified perturbation scale is also compared to our 91 GeV data and its parameter values are adjusted. We obtained an unfolded value for the mean charged multiplicity of 21.28±0.04±0.84, where the first error is statistical and the second is systematic.

APPENDIX.[Botany of Terra Australis.under which our collections were formed, both in the Investigator's voyage, and subsequently, during a stay of eighteen months, in New South Wales and Van Diemen's Island ; as also to state other sources from which additional materials have been obtained.By this means the reader will be better enabled to judge how far | am entitled to make those observations of a more general nature which he will find in the following pages.The first part of New Holland examined in captain Flinders's voyage was the South Coast, on various and distant points of which, and on several of its adjacent islands we landed, in cireumstances more or less favourable for our researches, The survey of this coast took place from West to East, and our first anchorage was in King George Third's Sound, in 35^ S. lat.and 118* E. lon.In this port we remained for three weeks, in the most favourable season for our pursuits ; and our collections of plants made chiefly on its shores and a few miles into the interior of the country, amount to nearly 500 species, exclusive of those belonging to the class Cryptogamia, which, though certainly bearing a small proportion to phenogamous plants, were not, it must be admitted, equally attended tox At our second anchorage, Lucky Bay of captain Flinders's chart, in 34° S. lat.and about 4° to the eastward of King George's Sound ; we remained only three days, but even in that short time added upwards of 100 species to our former collection.; Goose-Island Bay, in the same latitude and hardly one degree to the eastward of the second anchorage, where our stay was also very short, afforded us but few new plants ; and the remaining parts of the South Coast, on five distant points of which we landed, as well as on seven of its adjacent Islands, were still more barren, altogether producing only 200 additional species.The smallness of this number is to be accounted for, partly, no doubt, from the less favourable season in which this part of the coast was examined ; but it appeared to depend also in a considerable degree on its greater sterility, and especially that of its islands.Of New South Wales, or the East Coast of New Holland, scarcely any part beyond the tropic was examined in the voyage; our first landing after leaving Port Jackson being at Sandy Cape, in nearly 25^ S. lat.Between this and 21° S. lat, we had many, and upon the whole, favourable epportunities for observation, especially at Port Curtis, Keppel Bay, Port Coasts examined.

We study the inclusive momentum distribution of charged particles in multihadronic events produced in e+e− annihilations at ECM∼M(Z0). We find agreement with the analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from CM energies between 14 and 91 GeV, we study the dependence of the inclusive momentum distribution on the centre of momentum energy. We find that the analytical formulae describe the data over the entire energy range. Both the momentum distribution at a fixed energy and the change with energy are described by QCD shower Monte Carlo's which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and momentum spectra.

Journal Article Book Reviews Get access Contemporary Philosophy in Australia. Edited by Bobert Brown and C. D. Rollins. (London: Allen & Unwin. 1969. Pp. 216. Price 48s) Alan R. White Alan R. White Search for other works by this author on: Oxford Academic Google Scholar The Philosophical Quarterly, Volume 20, Issue 80, July 1970, Pages 280–281, https://doi.org/10.2307/2218413 Published: 01 July 1970

A GaAs: Si light-emitting-diode (LED) pumped 1.03-μm laser employing a YAG: Yb laser rod has been constructed with the rod and LED's cooled at ∼80 K. Pulsed operation with a peak laser power of 0.7 W is observed.

Tritium deposition in rainwater at Ottawa, Canada, is reported for the years 1953–1959. Correlation with the tritium content of drainage water in the district has allowed study of the hydro-dynamics of the water system. A turnover rate constant of 0·27 year−1 has been found for a storage reservior of 2·1 m. The. fraction of fresh precipitation in re-evaporated water has been estimated as 0·55±0·1. A deposition rate of cosmic tritium of 1·3±0·1 atoms/cm2 sec has been obtained from early data.

A study of the tritium content of rain- and sea-water samples collected during the past several years has been made. The tritium in 100–2000 gm. samples was concentrated 2000 to 20000 fold by electrolysis and the final concentrate counted as hydrogen in a Geiger counter. Good counter characteristics were obtained at hydrogen pressures up to one atmosphere by the use of an electronic quench unit of suitable deadtime in addition to the internal quench gas, ethylene. Rain and snow samples collected at Ottawa over the period 1951–1953 were found to range from 17.1 to 42.0 tritium atoms per 10 18 hydrogen atoms, averaging 26.6. Tritium values for Ottawa rain-water for 1954 showed marked effects of the thermonuclear tests in the Pacific in the spring of that year, rising 10 to 100 fold during the test period, then gradually returning to normal, demonstrating a half time for washout of 35 days. The average tritium concentration of the year’s rain is estimated to be 260 × 10 −18 T/H. Surface sea-water samples collected at widely separated sites in the latter half of 1954 and early 1955 showed tritium concentrations in the range 3.0–4.2 × 10 −18 T/H, a value which corresponds with the amount of artificially produced tritium observed in Ottawa rain. Subsurface samples collected at one station off the coast of Nova Scotia in mid-1955 showed an unexpected concentration level and pattern, having a T/H value of 32.4 × 10 −18 at the bottom depth of 600 ft., diminishing to a value of 5.4 × 10 −18 at the surface. This is not thought to be a result of thermonuclear testing and warrants further investigation.

The inclusive production rates of π±,K ± andp $$\bar p$$ inZ 0 decays have been measured with the OPAL detector at LEP. Using the energy loss measurement in the jet chamber, the momentum range up to the beam energy (45.6 GeV/c) has been covered. Differential cross sections and total particle yields are given. Comparisons of the inclusive momentum spectra and the total rates with predictions of the JETSET and the HERWIG Monte Carlo model are presented. The total single rates are found to be 17.05±0.43 π±, 2.42±0.13K ± and 0.92±0.11p $$\bar p$$ per hadronic event. Predictions of JETSET for cross sections and total rates agree very well for π±; however, for momenta greater than 4 GeV/c,K ± rates are underestimated and $$\bar p$$ rates are overestimated. Combined with data of other particle species there is evidence that the peak positions in the ξ=ln(1/x p ) distributions show a different mass dependence for mesons and baryons. However, both JETSET and HERWIG Monte Carlo predictions agree with the observed data.

A search for the minimal standard model Higgs boson (H0) has been performed with data from e+e− collisions in the OPAL detector at LEP. The analysis is based on approximately 8 pb−1 of data taken at centre-of-mass energies between 88.2 and 95.0 GeV. The search concentrated on the reaction e+e−→(e+e−, μ+μ−, vv or τ+τ−)H0, H0→(qq or τ+τ−) for Higgs boson masses above 25 GeV/c2. No Higgs boson candidates have been observed. The present study, combined with previous OPAL publications, excludes the existence of a standard model Higgs boson with mass in the range 3<mH0<44GeV/c2 at the 95% confidence level.

A study of b quark hadronisation is presented using inclusively reconstructed B hadrons in about four million hadronic Z decays recorded in 1992-2000 with the OPAL detector at LEP. The data are compared to different theoretical models, and fragmentation function parameters of these models are fitted. The average scaled energy of weakly decaying B hadrons is determined to be <xe>=0.7193+-0.0016(stat)+0.0036-0.0031(syst)

We have searched for Z0 decays into acoplanar pairs of leptons or jets. The data were recorded with the OPAL detector during an energy scan around the Z0 peak and correspond to about 17000 produced Z0,s. We have determined model independent limits on branching ratios for the Z0 to decay into pairs of heavy particles with subsequent decays leading to the above topologies. In the context of supersymmetric models, mass bounds close to the kinematic limit were obtained for the scalar leptons, ẽ, g̃m, g̃t, and for the chargino, X̃±.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAtomic fluorine spectra in the argon inductively coupled plasmaR. C. Fry, S. J. Northway, R. M. Brown, and S. K. HughesCite this: Anal. Chem. 1980, 52, 11, 1716–1722Publication Date (Print):September 1, 1980Publication History Published online1 May 2002Published inissue 1 September 1980https://doi.org/10.1021/ac50061a042RIGHTS & PERMISSIONSArticle Views338Altmetric-Citations65LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (652 KB) Get e-Alerts Get e-Alerts

Abstract A missense single-nucleotide polymorphism (SNP) in the immune modulatory gene IL1A has been associated with ovarian cancer risk (rs17561). Although the exact mechanism through which this SNP alters risk of ovarian cancer is not clearly understood, rs17561 has also been associated with risk of endometriosis, an epidemiologic risk factor for ovarian cancer. Interleukin-1α (IL1A) is both regulated by and able to activate NF-κB, a transcription factor family that induces transcription of many proinflammatory genes and may be an important mediator in carcinogenesis. We therefore tagged SNPs in more than 200 genes in the NF-κB pathway for a total of 2,282 SNPs (including rs17561) for genotype analysis of 15,604 cases of ovarian cancer in patients of European descent, including 6,179 of high-grade serous (HGS), 2,100 endometrioid, 1,591 mucinous, 1,034 clear cell, and 1,016 low-grade serous, including 23,235 control cases spanning 40 studies in the Ovarian Cancer Association Consortium. In this large population, we confirmed the association between rs17561 and clear cell ovarian cancer [OR, 0.84; 95% confidence interval (CI), 0.76–0.93; P = 0.00075], which remained intact even after excluding participants in the prior study (OR, 0.85; 95% CI, 0.75–0.95; P = 0.006). Considering a multiple-testing–corrected significance threshold of P &amp;lt; 2.5 × 10−5, only one other variant, the TNFSF10 SNP rs6785617, was associated significantly with a risk of ovarian cancer (low malignant potential tumors OR, 0.85; 95% CI, 0.79–0.91; P = 0.00002). Our results extend the evidence that borderline tumors may have a distinct genetic etiology. Further investigation of how these SNPs might modify ovarian cancer associations with other inflammation-related risk factors is warranted. Cancer Res; 74(3); 852–61. ©2013 AACR.

Quark and gluon jets with equal energies are identified in three-jet hadronicZ 0 events, using reconstructed secondary vertices from heavy quark decay in conjunction with energy ordering of the jets to anti-tag the gluon jets. Selection of jets from a symmetric event topology allows their properties to be compared in a simple and direct manner. The jets under study have an energy of about 24 GeV. It is observed that gluon jets have a larger angular width than quark jets and yield a softer particle energy spectrum. Correspondingly, the mean particle multiplicity is found to be larger for gluon than for quark jets. Correcting the distributions for residual misidentification of the quark and gluon jets, the ratio of mean particle multiplicty of gluon relative to quark jets is measured to be $$\frac{{\left\langle n \right\rangle _{gluon} }}{{\left\langle n \right\rangle _{quark} }} = 1.27 \pm 0.04(stat.) \pm 0.06(syst.),$$ where the jets are defined using thek ⊥ jet finder. The numerical value of this ratio is found to be sensitive to the choice of the jet algorithm. The experimental results are compared to Monte Carlo calculations which incorporate perturbative QCD along with different assumptions about the hadronization process.

Evidence is presented for kinematic and charge correlations of B mesons with charged pions and kaons. Using a new technique, a sample of over 80 000 partially reconstructed B mesons is obtained in 3.5·106 hadronic Z0 decays recorded using the OPAL detector at LEP. The invariant mass distributions of B+π− and B+K− combinations show enhancements consistent with the decays of P-wave resonances of a b antiquark and a light quark. We observe an excess of 1738±195 B+π− pairs with invariant masses in the range 5.60-5.85 GeV and an excess of 149±31 B+K− pairs with invariant masses in the range 5.80–6.00 GeV. Labeling the observed enhancements generically as B** we find $$\begin{gathered} \frac{{BR(Z^0 \to \bar b \to B^{**0} \to B^{(*) + } \pi ^ - )}}{{BR(Z^0 \to \bar b \to B^ + )}} = 0.18 \pm 0.04, \hfill \\ \frac{{BR(Z^0 \to \bar b \to B_s^{**0} \to B^{(*) + } K^ - )}}{{BR(Z^0 \to \bar b \to B^ + )}} = 0.026 \pm 0.008, \hfill \\ \end{gathered} $$ where B(*)+ indicates the sum of B+ and B*+ and the errors include statistical and systematic contributions. From a study of π-B charge-flavor correlations we conclude that the production flavor of a B meson can be tagged with the charge of a pion in an appropriately chosen kinematic region, and that the performance of this flavor tag compares favorably in the $$Z^0 \to q\bar q$$ environment with lepton-based tags.

A search for the minimal standard model Higgs boson has been performed with data from e+e− collisions in the OPAL detector at LEP. The analysis is based on 825 nb−1 of data taken at centre-of-mass energies between 88.3 and 95.0 GeV. The search concentrated on the reactions e+e−→(e+e− or μ+μ− or vv)H0,H0→(qq or τ+τ−), for Higgs masses above 3 GeV/c2. No Higgs boson candidates have been observed. The present study excludes the existence of a standard model H0 with mass in the range 3.0⩽mH⩽19.3 GeV/c2 at the 95% confidence level.

From a sample of 3308 e+e− → τ+τ− events with an estimated background of 1.9%, we find 964 τ → eνν, 903 τ → μνν, and 309 τ → π(K)ν candidates. Efficiency and background estimates determined from both Monte Carlo and control sample studies yield the following branching ratios: B(τ → eνν) = 17.4 ± 0.5 (stat) ± 0.4 (sys)%, B(τ → μνν) = 16.8 ± 0.5 ± 0.4%, and B(τ → π(K)ν) = 12.1 ± 0.7 ± 0.5%. These values are in good agreement with previous measurements. The measured lepton branching ratios, when combined with the world-average measured value for the τ lifetime, yield a ratio of the τ Fermi coupling constant to that of the lighter leptons given by Gτ/Ge,μ = 0.92 ± 0.04, where it is assumed Ge = Gμ ≡ Ge,μ. The average τ polarization at the Z° resonance is measured to be −0.01±0.09 from an analysis of the momentum spectra of the electron, muon, and pion candidates, implying that the ratio of vector to axial vector couplings of the τ to the Z° is ντ/ατ = 0.01 ± 0.04. The measurements of the average polarizations in the forward and backward hemispheres lead to the efficiency-corrected, forward-backward polarization asymmetry AFBpol = −0.22 ± 0.10, implying for the electron couplings to the Z° the ratio νe/αe = 0.15±0.07. Since these values for the tau and electron couplings are consistent with one another, we assume lepton universality to derive ν/α = 0.05 ± 0.04 and a value for the weak mixing angle of sin2θW = 0.237 ± 0.009, with no ambiguity introduced by the relative signs of ν and α.

We report on a measurement of the mass of the Z0 boson, its total width, and its partial decay widths into hadrons and leptons. On the basis of 25 801 hadronic decays and 1999 decays into electrons, muons or taus, selected over eleven energy points between 88.28 GeV and 95.04 GeV, we obtain from a combined fit to hadrons and leptons a mass of Mz = 91.154 ± 0.021 (exp) ± 0.030 (LEP) GeV, and a total width of Γz = 2.536 ± 0.045 GeV. The errors on Mz have been separated into the experimental error and the uncertainty due to the LEP beam energy. The measured leptonic partial widths are Γee = 81.2 ± 2.6 MeV, Γμμ = 82.6 ± 5.8 MeV, and Γττ = 85.7 ± 7.1 MeV, consistent with lepton universality. From a fit assuming lepton universality we obtain Γℓ+ ℓ− = 81.9 ± 2.0 MeV. The hadronic partial width is Γhad = 1838 ± 46 MeV. From the measured total and partial widths a model independent value for the invisible width is calculated to be Γinv = 453 ± 44 MeV. The errors quoted include both the statistical and the systematic uncertainties.

Quark and gluon jets in e+e− three-jet events at LEP are identified using lepton tagging of quark jets, through observation of semi-leptonic charm and bottom quark decays. Events with a symmetry under transposition of the energies and directions of a quark and gluon jet are selected: these quark and gluon jets have essentially the same energy and event environment and as a consequence their properties can be compared directly. The energy of the jets which are studied is about 24.5 GeV. In the cores of the jets, gluon jets are found to yield a softer particle energy spectrum than quark jets. Gluon jets are observed to be broader than quark jets, as seen from the shape of their particle momentum spectra both in and out of the three-jet event plane. The greater width of gluon jets relative to quark jets is also visible from the shapes of their multiplicity distributions. Little difference is observed, however, between the mean value of particle multiplicity for the two jet types.

Bose-Einstein correlations between like-sign charged track pairs have been studied in e+e− annihilation hadronic events at centre-of-mass energies around the Z0 peak as a function of Q, the four-momentum difference of the pair. The measurement was performed with the OPAL detector at LEP. Assuming the charged tracks to be pions, the observed Bose-Einstein enhancement was used to extract the values of the strength of the effect and the radius of the pion emitting source, which were found to be λ=0.866±0.032±0.140 and R0=0.928±0.019±0.150 fm, respectively, where the first error is statistical and the second is systematic. The results do not show significant variation in comparison to e+e− annihilation measurements at lower centre-of-mass energies. If non-pion track contamination is taken into account, the value of the strength λ becomes consistent with unity.

We have measured the elastic cross section for $\mathrm{pp}$, $\overline{p}p$, ${\ensuremath{\pi}}^{+}p$, ${\ensuremath{\pi}}^{\ensuremath{-}}p$, ${K}^{+}p$, and ${K}^{\ensuremath{-}}p$ scattering at incident momenta of 70, 100, 125, 150, 175, and 200 GeV/c. The range of the four-momentum transfer squared $t$ varied with the beam momentum from $0.0016\ensuremath{\le}\ensuremath{-}t\ensuremath{\le}0.36$ (${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ at 200 GeV/c to $0.0018\ensuremath{\le}\ensuremath{-}t\ensuremath{\le}0.0625$ (${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ at 70 GeV/c. The conventional parametrization of the $t$ dependence of the nuclear amplitude by a simple exponential in $t$ was found to be inadequate. An excellent fit to the data was obtained by a parametrization motivated by the additive quark model. Using this parametrization we determined the ratio of the real to the imaginary part of the nuclear amplitude by the Coulomb-interference method.

A charge hyperon beam has been brought into operation at the CERN SPS. Particles are identified by a DISC Čerenkov counter, and decay products are analysed by a magnetic spectrometer. Cross sections for the inclusive production of π+, K+, p, Σ+, Σ−, ζ−, d, and π−, K−, p, Σ+, Σ−, ζ−, ω−, d in the forward direction have been measured at laboratory momenta between 70 and 130 GeV/c. This range of momenta corresponds to 0.35 ⩽ x ⩽ 0.66 for an incident proton momentum of 200 GeV/c. Antihyperon (Σ−, ζ−, Σ+) and Σ+ and ω− fluxes have been measured for the first time in a hyperon beam. Scaling behaviour is observed when the data are compared with the results from other experiments. The inclusive particle production cross sections have a (1 − x)n dependence, where n is characteristics of the particle. A search has been made for new particles in the mass range 2–10 GeV/c2. No evidence is found for such particles.

Abstract Purpose: An assay for the single-nucleotide polymorphism (SNP), rs61764370, has recently been commercially marketed as a clinical test to aid ovarian cancer risk evaluation in women with family histories of the disease. rs67164370 is in a 3′-UTR miRNA binding site of the KRAS oncogene and is a candidate for epithelial ovarian cancer (EOC) susceptibility. However, only one published article, analyzing fewer than 1,000 subjects in total, has examined this association. Experimental Design: Risk association was evaluated in 8,669 cases of invasive EOC and 10,012 controls from 19 studies participating in the Ovarian Cancer Association Consortium, and in 683 cases and 2,044 controls carrying BRCA1 mutations from studies in the Consortium of Investigators of Modifiers of BRCA1/2. Prognosis association was also examined in a subset of five studies with progression-free survival (PFS) data and 18 studies with all-cause mortality data. Results: No evidence of association was observed between genotype and risk of unselected EOC (OR = 1.02, 95% CI: 0.95–1.10), serous EOC (OR = 1.08, 95% CI: 0.98–1.18), familial EOC (OR = 1.09, 95% CI: 0.78–1.54), or among women carrying deleterious mutations in BRCA1 (OR = 1.09, 95% CI: 0.88–1.36). There was little evidence for association with survival time among unselected cases (HR = 1.10, 95% CI: 0.99–1.22), among serous cases (HR = 1.12, 95% CI = 0.99–1.28), or with PFS in 540 cases treated with carboplatin and paclitaxel (HR = 1.18, 95% CI: 0.93–1.52). Conclusions: These data exclude the possibility of an association between rs61764370 and a clinically significant risk of ovarian cancer or of familial ovarian cancer. Use of this SNP for ovarian cancer clinical risk prediction, therefore, seems unwarranted. Clin Cancer Res; 17(11); 3742–50. ©2011 AACR.

The Average Response Computer has proved a valuable tool for measuring statistics of neuroelectric activity, particularly of evoked responses. One of the most important aspects of the instrument is it ability to operate "on line," thus enabling the experimenter to observe and modify on the basis of the calculated results while the experiment is in progress. Although the ARC was designed to operate in fixed modes, it has demonstrated a gratifying flexibility in the face of new experimental requirements. With respect to future developments, we feel that greater speed of operation and extension to multiple channels would further extend the range of applications and increase the versatility of the device.

The process $\mathrm{e}^+\mathrm{e}^- \to\gamma\gamma(\gamma)$ is studied using data collected by the OPAL detector at LEP between the years 1997 and 2000. The data set corresponds to an integrated luminosity of 672.3 pb-1 at centre-of-mass energies lying between 181 GeV and 209 GeV. Total and differential cross-sections are determined and found to be in good agreement with the predictions of QED. Fits to the observed angular distributions are used to set limits on parameters from several models of physics beyond the Standard Model such as cut-off parameters, contact interactions of the type $\mathrm{e}^+\mathrm{e}^- \gamma\gamma$ , gravity in extra spatial dimensions and excited electrons. In events with three photons in the final state the mass spectrum of photon pairs is investigated. No narrow resonance $X\to\gamma\gamma$ is found and limits are placed on the product of the $\rm X \gamma$ production cross-section and branching ratio.

A search for the Standard Model Higgs boson has been performed with the OPAL detector at LEP based on the full data sample collected at s≈192–209 GeV in 1999 and 2000, corresponding to an integrated luminosity of approximately 426 pb−1. The data are examined for their consistency with the background-only hypothesis and various Higgs boson mass hypotheses. A lower bound of 109.7 GeV is obtained on the Higgs boson mass at the 95% confidence level. At higher masses, the data are consistent with both the background and the signal-plus-background hypotheses.

The cross section of the pure QED process e+e−→γγ has been measured using data accumulated during the 1989 and 1990 scans of the Z0 resonance at LEP. Both the energy dependence and the angular distribution are in good agreement with the QED prediction. Upper limits on the branching ratios of Z0→γγ, Z0→π0γ and Z0→ηγ have been set at 1.4×10 −4, 1.4×10−4 and 2.0×10−4 respectively. Lower limits on the cutoff parameters of the modified electron propagator have been found to be Λ+ > 117 GeV and Λ− > 110 GeV. The reaction e+e− → γγγ has also been studied and was found to be consistent with the QED prediction. An upper limit on the branching ratio of Z0→γγγ has been set at 6.6 × 10−5. All the limits are given at 95% confidence level.

A search has been performed for unstable charged scalar particles (S±) such as technipions or charged Higgs bosons, pair-produced in e+e− annihilation at energies near the Z0 pole. No evidence for such particles was observed in the decay modes e+e−→S+S−→(cs)(τv), (τv) (τv)and(cs)(cs). A lower limit (at the 95% CL ) of 35 Gev/c2 is obtained for the mass of the charged scalar particles, independent of the branching ratio.

We report on a search for new quarks in hadronic Z° decays. From the event shape analysis of a data sample containing 2185 multihadronic annihilation events, we observe no evidence for the top or b' quarks. We derive limits for the top and b' quark masses under the assumption of various possible standard model and non-standard model decay schemes. Our search is sensitive to quark masses larger than 23 GeV/c2; it yields the following lower limits at a 95% confidence level: 44.5 GeV/c2 for the top quark mass and 45.2 GeV/c2 for the b′ quark mass.

Nonresonant, low-energy (visible-near infrared) atomic nitrogen transitions from high-energy (11 to 14.4 eV) doublet and quartet excited N(I) states are observed in the 1.5 to 2.2 kW argon inductively coupled plasma (ICP) when gaseous compounds containing this element (N) are introduced as samples. A Table of ICP excited nitrogen (I) lines and relative emission intensities from 2225 to 10 950 Å is presented. A number of new nitrogen lines are observed for which transitions have not been assigned. The ICP nonresonance emission spectrum of atomic nitrogen [N(I)] is found to be especially good in the near infrared region. The use of near infrared nonresonant N(I) lines for the analytical detection of nitrogen is reported. The relative intensity of N(I) emission (derived from N 2 samples) is at a maximum between the turns of the rf load coil. An “equal intensity” contour “map” of N(I) emission in the ICP is presented using N 2 as the sample. The present limit of nitrogen detection in argon for nonoptimized conditions is 1.0 ppm (v/v) using continuous sample introduction (limited by photomultiplier noise). For gas sampling loop injections, the present detection limit is 0.3 μg (limited by atmospheric leakage or permeation contamination into the sampling loop system). Considerable improvement is expected in the future. The relative contributions to the baseline signal of: (1) atmospheric nitrogen entrainment in the argon plasma, (2) atmospheric permeation into the present Teflon gas sampling loop system, and (3) argon tank contaminants are evaluated. Suggestions for further improvement are given. The response is linear, and the short-term precision for repetitive introduction of samples containing 20 μg of N 2 is 0.4% RSD using a 157 μl Teflon gas sampling loop.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNear-infrared atomic oxygen emissions in the inductively coupled plasma and oxygen-selective gas-liquid chromatographyR. M. Brown and R. C. FryCite this: Anal. Chem. 1981, 53, 3, 532–538Publication Date (Print):March 1, 1981Publication History Published online1 May 2002Published inissue 1 March 1981https://doi.org/10.1021/ac00226a034Request reuse permissionsArticle Views72Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (887 KB) Get e-Alertsclose Get e-Alerts

Hadronic event shape distributions from e+e- annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong coupling {\alpha}S. The results are based on QCD predictions complete to the next-to- next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is {\alpha}S(mZ0) = 0.1201 {\pm} 0.0008(stat.) {\pm} 0.0013(exp.) {\pm} 0.0010(had.) {\pm} 0.0024(theo.). while the combined NNLO+NLLA result is {\alpha}S(mZ0) = 0.1189 {\pm} 0.0008(stat.) {\pm} 0.0016(exp.) {\pm} 0.0010(had.) {\pm} 0.0036(theo.). The completeness of the NNLO and NNLO+NLLA results with respect to missing higher order contributions, studied by varying the renormalization scale, is improved compared to previous results based on NLO or NLO+NLLA predictions only. The observed energy dependence of {\alpha}S agrees with the QCD prediction of asymptotic freedom and excludes the absence of running.

A new generation of vacuum phototriodes (VPTs) has been developed for application in the end-cap sub-system of the crystal electromagnetic calorimeter (ECAL) for the CMS experiment at the CERN Large Hadron Collider (LHC). These VPTs must operate with high reliability for at least 10 years in an extremely hostile environment. Results are presented from an extensive programme of tests, demonstrating that the required properties of significant gain in a 4 T magnetic field, resistance to ionising radiation, and stable operation with large photocurrents can all be satisfied in a robust, compact, inexpensive device.

Current methods for sampling and measuring tritium are described. Although the basic techniques have not changed significantly over the last 10 y, there have been several notable improvements in tritium measurement instrumentation. The design and quality of commercial ion-chamber-based and gas-flow-proportional-counter-based tritium monitors for tritium-in-air have improved, an indirect result of fusion-related research in the 1980s. For tritium-in-water analysis, commercial low-level liquid scintillation spectrometers capable of detecting tritium-in-water concentrations as low as 0.65 Bq L−1 for counting times of 500 min are available. The most sensitive method for tritium-in-water analysis is still 3He mass spectrometry. Concentrations as low as 0.35 mBq L−1 can be detected with current equipment. Passive tritium-oxide-in-air samplers are now being used for workplace monitoring and even in some environmental sampling applications. The reliability, convenience, and low cost of passive tritium-oxide-in-air samplers make them attractive options for many monitoring applications. Airflow proportional counters currently under development look promising for measuring tritium-in-air in the presence of high gamma and/or noble gas backgrounds. However, these detectors are currently limited by their poor performance in humidities over 30%.

Using muon candidates in 133 000 hadronic decays of the Z0, recorded by the OPAL detector at LEP, we have measured the fraction of events containing semi-leptonic decays of b flavoured hadrons. An analysis based on fitting the shape of the momentum and transverse momentum distributions of the muon candidates gave the result: (Γ(Z0→bb)Γ(Z0→hadrons))×Br(b→μ)=0.0226±0.0007±0.0013, and also yielded: (Γ(Z0→cc)Γ(Z0→hadrons))×Br(c→μ)=0.0176±0.0025±0.0042. Using the charge of the muon and the angle of the event thrust axis with respect to the electron beam, in a b-enriched event sample, we measured the forward-backward asymmetry for Z0 → bb decays. Without correction for B0B0 mixing, the asymmetry was found to be AbFB = 0.072±0.042±0.010.

The production of the octet and decuplet baryons Λ, Ξ−, Σ(1385)±, Ξ(1530)0 and Ω− and the corresponding antibaryons has been measured in a sample of 485 000 hadronic Z0 decays. Results on differential and integrated cross sections are presented. The differential cross section of Λ baryons is found to be softer than the one predicted by the Jetset and Herwig Monte Carlo generators. The measured decuplet yields are found to disagree with the simple diquark picture where only one tuning parameter for spin 1 diquarks is used. Comparisons of the momentum spectra for Λ and Ξ− with the predictions of an analytical QCD formula are also presented.

The observation and measurement of the time-dependence of B0d↔B0d mixing are described. The B0d meson is reconstructed in final states that contain a D∗− and an ℓ+, where the b flavour of the B0d at decay time is tagged by the electric charge of the lepton. A new and efficient method, using a jet charge technique, is developed for identifying the b flavour of the produced B0d. From a sample of 556 D∗±ℓ∓ candidates reconstructed in the OPAL data collected during 1990–1993, the B0d↔B0d oscillation frequency is measured to be Δmd = 0.508 ± 0.075 (stat) ±0.025(syst) ps−1 giving an oscillation parameter of χd = 0.73 ± 0.11 (stat) ±0.08 (syst), where 0.076 of the systematic error on χd arises from the uncertainty on the B0d lifetime.

The measurement of scintillation light from the lead tungstate crystals of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) poses a substantial technical challenge, particularly in the endcap regions, where the radiation levels are highest. The photodetectors must be fast, sensitive, radiation-hard, and operate with significant internal gain in a magnetic field of 4 Tesla. The measured performance characteristics of the first batches of series production vacuum phototriodes (VPT), developed to satisfy the needs of CMS, will be described.

A search for scalar leptoquarks has been performed with data from the OPAL detector at the e+e− storage ring LEP. In a data sample corresponding to an integrated luminosity of 6.3 pb−1 no evidence for leptoquark production was observed where the leptoquark decays into a quark and either a charged lepton (e, μ, τ) or a neutrino. An upper limit of 1.7 pb on the production cross section for leptoquarks is obtainedassuming a branching ratio of 50% for the decay of the leptoquark into the channels with a charged lepton. Lower limits on the leptoquark mass between 41.4 and 46.4 GeV/c2 at 95% CL are obtained, depending on the effecte SU(2) × U(1) invariant couplings assigned to the leptoquark.

Data taken with the OPAL detector at LEP during a scan of the Z0 resonance were searched for evidence of neutral heavy leptons that decay via mixing. Four different decay modes of the neutral heavy lepton are considered: L0→eW∗, L0→μW∗, L0→τW∗, and L0→vZ∗. No evidence is seen of a neutral heavy lepton signal; branching fraction limits in the range of 10−3–10−4 are set for Z0→L0L0 and for Z0→vL0 (orvL0) relative to Z0→hadrons.

The amplitude of the signal collected from the PbWO4 crystals of the CMS electromagnetic calorimeter is reconstructed by a digital filtering technique. The amplitude reconstruction has been studied with test beam data recorded from a fully equipped barrel supermodule. Issues specific to data taken in the test beam are investigated, and the implementation of the method for CMS data taking is discussed.

Evidence for narrow states produced by Σ− interactions in beryllium, and decaying into (Λp + pions), has been obtained in an experiment at the CERN SPS hyperon beam. At 3.1 GeV/c2, the (Λpπ+ π+), (Λpπ+ π+ π−) and (Λpπ+ π−) effective mass distributions show an excess of 45, 19 and 62 events above a background of 50, 28 and 187, respectively. The possibility that these three signals are statistical fluctuations is remote. The observed widths of the signals are compatible with the mass resolution of the apparatus, 24 MeV/c2 FWHM. We have not been able to find an interpretation of the quantum numbers of the final states, which are baryon number 0, strangeness −1 and charge +1, 0 and −1.

A clog-free Babington slurry nebulizer system is presented for direct current plasma (DCP) emission spectrometry. The DCP is unique in that the torch tip opening at the entry point into this plasma is presently ∼5 times wider than that of the inductively coupled plasma and ∼10 times wider than that of premixed flame burner slots. The combination of this enlarged DCP torch tip opening and a Babington slurry nebulizer results in an overall system for spectrochemical analysis that is virtually unrestricted as to the direct nebulization and aerosol transport of homogenized solid samples such as animal tissue. Beef liver is briefly homogenized for 2 min and then directly nebulized into the plasma. A sample may be nebulized continuously without torch tip clogging. This eliminates the need for transient nebulization and allows for extended electronic integration times as well as wavelength scanned, spectral background correction procedures. Elements such as Cu, Zn, Ca, and P are detected in liver tissue within less than 10 min from the time the unprepared solid sample is received in the laboratory. The effects of Babington gas orifice diameter, argon flow rate, and sample consumption rate are studied. The DCP is found to have a remarkably wide range of gas flow rates acceptable for nebulizer operation. The use of near forward laser Fraunhofer diffraction is reported for the direct measurement of droplet size distributions on a nonintrusive basis as the aerosols emerge from spray chambers of spectrochemical interest.

This paper presents the results of a counter experiment at the Rutherford Laboratory, in which the polarization parameter in π+p elastic scattering was measured. Data were taken at 64 incident pion momenta between 0.60 and 2.65 GeV/c. The results are found to be in generally good agreement with those of other experiments, and have substantially higher precision at many momenta.

Invasive ovarian cancer is a significant cause of gynecologic cancer mortality.We examined whether this mortality was associated with inherited variation in approximately 170 candidate genes/regions [993 single-nucleotide polymorphisms (SNPs)] in a multistage analysis based initially on 312 Mayo Clinic cases (172 deaths). Additional analyses used The Cancer Genome Atlas (TCGA; 127 cases, 62 deaths). For the most compelling gene, we immunostained Mayo Clinic tissue microarrays (TMA, 326 cases) and conducted consortium-based SNP replication analysis (2,560 cases, 1,046 deaths).The strongest initial mortality association was in HGF (hepatocyte growth factor) at rs1800793 (HR = 1.7, 95% CI = 1.3-2.2, P = 2.0 × 10(-5)) and with overall variation in HGF (gene-level test, P = 3.7 × 10(-4)). Analysis of TCGA data revealed consistent associations [e.g., rs5745709 (r(2) = 0.96 with rs1800793): TCGA HR = 2.4, CI = 1.4-4.1, P = 2.2 × 10(-3); Mayo Clinic + TCGA HR = 1.6, CI = 1.3-1.9, P = 7.0 × 10(-5)] and suggested genotype correlation with reduced HGF mRNA levels (P = 0.01). In Mayo Clinic TMAs, protein levels of HGF, its receptor MET (C-MET), and phospho-MET were not associated with genotype and did not serve as an intermediate phenotype; however, phospho-MET was associated with reduced mortality (P = 0.01) likely due to higher expression in early-stage disease. In eight additional ovarian cancer case series, HGF rs5745709 was not associated with mortality (HR = 1.0, CI = 0.9-1.1, P = 0.87).We conclude that although HGF signaling is critical to migration, invasion, and apoptosis, it is unlikely that HGF genetic variation plays a major role in ovarian cancer mortality. Furthermore, any minor role is not related to genetically-determined expression.Our study shows the utility of multiple data types and multiple data sets in observational studies.

In the wake of highly visible institutionalized anti-Black violence, this study examined how sense of belonging manifests among Black students at historically white colleges. The findings speak to the need to expand upon the conceptualization of sense of belonging for Black students, particularly considering the history of racial trauma in the United States. The analysis draws from a lineage of critical race and afro-pessimist discourse to make connections between the participants' experiences and the people who preceded them. Implications for practice are introduced that consider how institutions can support the critical agency of Black students.

Ce3+-doped scintillating glasses with high light yield and high density are promising candidates for use in electromagnetic calorimeters for particle physics applications. Here, Ce3+-doped glasses with up to 30 mol% Gd2O3 in the system SiO2–B2O3–Al2O3–Gd2O3 have been prepared. Substitutions of Al2O3 by Ga2O3, SiO2 by GeO2 and oxygen by fluorine have been made to increase the density, the resulting effects on optical absorption, luminescence and scintillating properties have been investigated. The glasses made have a high density of 5.0–5.5 × 103 kg m−3. Substitution of fluorine for oxygen resulted in a large increase in the light yield.

The production dynamics of baryon-antibaryon pairs are investigated using hadronic Z0 decays, recorded with the OPAL detector, which contain at least two identified Λ baryons. The rapidly difference for ΛΛ pairs shows the correlations expected from models with a chain-like production of baryon-antibaryon pairs. If the baryon number of a Λ is compensated by a Λ, the Λ is found with a probability of 53% in an interval of ±0.6 around the Λ rapidity. This correlation strength is weaker than predicted by the Herwig Monte Carlo and the Jetset Monte Carlo with a production chain of baryon-antibaryon, and stronger than predicted by the UCLA model. The observed rapidity correlations can be described by the Jetset Monte Carlo with a dominant production chain of baryon-meson-antibaryon, the popcorn mechanism. In addition to the short range correlations, one finds an indication of a correlation of ΛΛ pairs in opposite hemispheres if both the Λ and the Λ have large rapidities. Such long range correlations are expected if the primary quark flavours are compensated in opposite hemispheres and if these quarks are found in energetic baryons. Rates for simultaneous baryon and strangeness number compensation for ΛΛ, Ξ−Ξ+ and Ξ−Λ (Λ+ Λ) are measured and compared with different Monte Carlo models.

From the observed yield and properties of isolated energetic photons in the reaction e+e−→Z0→hadrons+γ measured with the OPAL detector at LEP, evidence for final state radiation from primary quarks is obtained. Combined with the measurement of the total hadronic width of the Z0, the observed rate allows the extraction of the electroweak coupling constants of up and down type quarks: ν132 + a132 = 1.24±0.47 and ν232 + a232 = 1.72±0.70 No evidence for additional photon production from anomalous decays of the Z0 or from decays of new particles is found. This measurement limits the contribution to the total Z0 width from such sources to be less than 8.2 MeV at the 95% confidence level.

A search for the single production of doubly-charged Higgs bosons is performed using e+e− collision data collected by the OPAL experiment at centre-of-mass energies between 189 GeV and 209 GeV. No evidence for the existence of H±± is observed. Upper limits are derived on hee, the Yukawa coupling of the H±± to like-signed electron pairs. A 95% confidence level upper limit of hee< 0.071 is inferred for M(H±±)<160 GeV assuming that the sum of the branching fractions of the H±± to all lepton flavour combinations is 100%. Additionally, indirect constraints on hee from Bhabha scattering at centre-of-mass energies between 183 GeV and 209 GeV, where the H±± would contribute via t-channel exchange, are derived for M(H±±)<2 TeV. These are the first results both from a single production search and on constraints from Bhabha scattering reported from LEP.

Preliminary qualitative multielemental inductively coupled plasma atomic spectra of C, H, N, and O are presented using a low dispersion, near infrared and red photodiode array spectrometer. Simple spectra of reasonable intensity are obtained with short (4 ms) integration times. Sensitivity and dispersion considerations are sharply contrasted with those conventionally associated with ultraviolet photodiode array spectra of metals in the inductively coupled plasma.

We measure the mass of the τ to be 1775.1±1.6(mcnstat.)±1.0(mcnsys.) MeV using τ from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged τ. The relative mass difference is found to be smaller than 3.0×10−3 at the 90% confidence level.

We present an update with increased statistics to our published analysis of hadronic and leptonic cross sections and of the leptonic forward-backward asymmetries ine + e − collisions. The published results were based on a total 454 000 hadronic and 58 000 leptonic events. This analysis adds 733 000 hadronic and 88 000 leptonic events recorded at theZ 0 peak in 1992 by the OPAL experiment at LEP. A model independent analysis ofZ 0 parameters based on an extension of the improved Born approximation leads to tests of lepton universality and gives an interpretation of the results within the Standard Model framework. We also present a model independent test for new physics.

A study of b quark fragmentation at LEP is presented using a sample of semileptonic B decays containing a fully reconstructed charm meson. The data are compared to several theoretical models for heavy quark fragmentation; the free parameters in these models are fitted and the sensitivity of the model parameters to the rate of P-wave B meson production is studied. The mean scaled energy fraction of B0 and B+ mesons has been determined to be <xE> = 0.695 ± 0.006 ± 0.003 ± 0.007, where the errors are statistical, systematic and model dependence respectively. This result is consistent with previous, less direct measurements from inclusive leptonic B decays. Also presented is a model independent fit to the shape of the energy distribution of weakly decaying B mesons at LEP.

Gluon jets with about 39 GeV energy are identified in hadronic Z0 decays by tagging two jets in the same hemisphere of an event as quark jets. Identifying the gluon jet to be all the particles observed in the hemisphere opposite to that containing the two tagged jets yields an inclusive gluon jet definition corresponding to that used in analytic calculations, allowing the first direct test of those calculations. In particular, this jet definition yields results which are only weakly dependent on a jet finding algorithm. We find rch.=1.552±0.0041 (stat) ±0.061 (syst.) for the ratio of the mean charged particle multiplicity in gluon jets to that in light quark uds jets, where the uds jets are identified using an inclusive jet definition similar to that used for the gluon jets. Our result is in general agreement with the prediction of a recent analytic calculation which incorporates energy conservation into the parton shower branching processes, but is considerably smaller than analytic predictions which do not incorporate energy conservation.

A description is given of the OPAL end cap electromagnetic calorimeters which consist of leadglass instrumented with vacuum photo triodes. Test results are presented showing linearity, energy and position resolution measured in an electron beam whilst the calorimeter is subject to magnetic fields up to 1.0 T. The response to hadrons is also discussed. Finally, radiation damage and recovery of the leadglass is reported.

Using data from e+e− collisions collected with the OPAL detector during the 1990 LEP run, a search was mode for a low mass Higgs boson (H0) with arbitrary decay mode. The existence of a minimal standard model H0 with mass in the range 0 ⩽ mH ⩽ 11.3 GeV/c2 is excluded at the 95% confidence level for all possible decay modes of the H0. Limits on the production of Higgs bosons predicted by the minimal supersymmetric standard model and new scalar particles that couple to the Z0 are presented as a function of the scalar mass.

Performance tests of some aspects of the CMS ECAL were carried out on modules of the "barrel" sub-system in 2002 and 2003. A brief test with high energy electron beams was made in late 2003 to validate prototypes of the new Very Front End electronics. The final versions of the monitoring and cooling systems, and of the high and low voltage regulation were used in these tests. The results are consistent with the performance targets including those for noise and overall energy resolution, required to fulfil the physics programme of CMS at the LHC.

In an experiment in the CERN SPS charged hyperon beam, a sample of 16 000Ω− decays was collected at an Ω− momentum of 131 GeV/c the Ω− lifetime, the branching ratios and decay asymmetry parameters for the main decay modes were measured, giving: τΩ−=(0.823±0.015)×10−10s, Γ(Ω−→ΛK−)Γ(Ω−-→all)=0.675±0.008, α(Ω−→ΛK−)= −0.025±0.028, Γ(Ω−→Ξ0π−)Γ(Ω−→all) = 0.236±0.008, α(Ω−→Ξ0π−)=0.09±0.14, Γ(Ω−→Ξ−π0)Γ(Ω−→all)=0.089±0.005, α(Ω−→Ξ−π0)=0.05±0.21. For the rare decay modes, the following results for the branching ratios were obtained: if Γ(Ω−→Ξ0e−ν)Γ(Ω−→all)=(0.56±0.28)×10−2, ifΓ(Ω−→Ξ−π+π−)(Γ(Ω→all)=(3.7−1.1+3.6)×10−4, Γ(Ω−→Ξ−γ)(Γ(ω−→all)<2.2×10−3 at the 90% confidence level, Γ(Ω−→Λπ−)(Γ(Ω−→all)<1.9×10−4 at the 90% confidence level. A sample of 32 000 Ξ− decays collected under the same experimental conditions gave a new measurement of the Ξ− lifetime: τΞ−=(1.652±0.051)×10−10 s. Combining the measurements of the present experiment with those obtained in a previous experiment in the SPS hyperon beam gives: ifτΩ−=(0.823±0.013)×10−10 s, Γ(Ω−→ΛK−)Γ(Ω−→all=0.678±0.007, Γ(Ω−→Ξ0π−)Γ(Ω−→all)=0.236±0.007, Γ(Ω−→Ξ−π0)Γ(Ω−→all=0.086±0.004, Γ(Ω−→Ξ−π+π−)Γ(Ω−→all=(4.3−1.3+3.4)×10−4. The experimental results are compared with theoretical calculations.

The charged hyperon beam at the CERN Super Proton Synchrotron (SPS) has been used to collect data on semileptonic decays of Σ−, Ξ−, and Λ. In this article we report results on the $$\sum \to ne\bar v$$ decay mode. A magnetic channel selected 100 GeV/c (130 GeV/c) negatively charged particles produced in the forward direction by interaction of the 210 GeV/c (240 GeV/c) SPS proton beam on a BeO target. The Σ− hyperons were identified in a DISC Čerenkov counter, and the negatively charged decay particle was analysed by a magnetic spectrometer. The neutron direction was obtained from the Σ− decay vertex and from the impact point measured in a neutron detector. Electron-hadron discrimination was achieved by the combined use of lead-glass and transition radiation detectors. The $$\sum \to ne\bar v$$ branching ratio measurement gave a value of (0.96±0.05) ×10−3. Measurements of the centre-of-mass distributions (baryon kinetic energy, electron-antineutrino correlation, and Dalitz plot distributions) yield the axial-vector to vector form factor ratio |g 1/f 1|=0.34 ±0.05. From the study of the electron momentum spectrum, the negative sign ofg 1/f 1, which is expected within the Cabibbo theory framework, is favoured by at least 2.6 standard deviations. The effects ofq 2-dependence off 1 andg 1 and of radiative corrections, the measurement of the weak magnetism form factorf 2, and the effect of possible second-class current terms are discussed. Results on the other Ξ−, Σ−, and Λ semileptonic decays are reported in separate articles.

Results are presented of differential cross-section measurements for the reaction π−p→π0n;π0→γγ at 22 incident pion momenta between 618 and 2724 MeV/c. The results are in good agreement with those of other experiments. They represent the first comprehensive set of high statistics measurements of the π−p charge-exchange differential cross section at closely spaced momenta in the resonance region.

Polarized cross sections for the reaction π−p → ηn have been measured at 12 incident momenta between 1171 and 2267 MeV/c. The data show that the polarization is small in the forward direction and there is a general trend for it to be large and positive near cos θ∗ = 0.2. These are the first published results on polarization effects in this channel in the resonance region. An energy-dependent partial-wave analysis has been performed and the couplings and branching fractions for decays of nucleon resonances to this channel are presented.

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated.

The experimental work of the Eaton–Peabody Laboratory of Auditory Physiology requires chambers unusually free of ambient acoustic, vibratory, and electric noise, so that small mechanical or electric signals in response to low-level sounds can be measured. This paper deals with the problems that arose in setting of criteria, the design, and the construction of such chambers, and reports on the evaluation of their performance. The ambient acoustic noise is well below the human threshold of hearing even with the ventilation system operating. The noise reduction between the control rooms and the chambers is almost 80 dB at 250 Hz and more than 90 dB above 500 Hz. The octave-band ambient vibration acceleration level at the experimental tables in the chambers is below −120 dB re lg. Subject Classification: 55.40; 65.10.

A new class of intermediate-gain laser materials for rare-earth ions, based upon the principle of inhomogeneous broadening of spectral lines in mixed-compound crystals, is reported. Spectroscopic evidence for Nd in YAl0.6Ga0.4G mixed garnets is presented which shows a cross-section reduction of 3.3 compared to Nd in YAlG. Other physical properties of the mixed garnets, in particular the thermal conductivity, are not degraded; consequently, the Nd-doped mixed garnet materials may prove important for increased-energy/pulse high-average-power Q-switched laser applications.

Results are presented of polarization parameter measurements for the reaction π−p→π0n at 22 momenta between 617 and 2267 MeV/c. These results are generally in agreement with those of previous measurements and in qualitative agreement with predictions of phase-shift analyses. Together with the recently published differential cross-section measurements, they provide a comprehensive set of data for this reaction in the resonance region.

Abstract The Janus kinase 2 (JAK2) gene is located on chromosome 9p24.1 and encodes a non-receptor tyrosine kinase that plays a central role in cytokine and growth factor signaling. The JAK2 protein is especially important for controlling the production of blood cells from hematopoietic stem cells. In fact, the JAK2 mutation at amino acid 617 (Valine 617 to Phenylalanine, V617F) is the most frequently detected mutation in myeloproliferative neoplasms (MPN), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). This dominant gain-of-function V617F mutation results in constitutive tyrosine phosphorylation activity, leading to uncontrolled blood cell production, including increased numbers of erythrocytes, neutrophils, and platelets. To detect the JAK2 V617F mutation in DNA from patient blood samples, we developed a unique real-time PCR assay using our proprietary XNA technology that enables the assay to selectively amplify the mutant sequence by using a synthetic DNA analog XNA (Xenonucleic Acid). The JAK2 V617F mutation detection assay is designed to detect a valine-to-phenylalanine mutation at amino acid 617 (V617F). PCR primers, TaqMan probes, and XNA were designed for the JAK2 V617F mutation, along with primers and probes for an internal control gene in the duplex setting. The analytical performance of the assay was verified and validated using a variety of control samples. The results revealed that the XNA completely suppressed the amplification of wildtype sequence while only the V617F mutant sequence was amplified. The JAK2 V617F mutation detection assay is highly reproducible with intra- and inter-assay coefficients of variation of less than 10%. Results for the assay’s analytical sensitivity indicated that V617F could be detected with about 0.25% mutant allele frequency in 10 ng DNA input. In addition, no significant cross-amplification between V617F and V617I was observed. Thus, the JAK2 V617F mutation detection assay is specific for the V617F mutation. The JAK2 V617F mutation detection assay, using XNA-based technology, provides high sensitivity and specificity to detect the JAK2 V617F mutation. Thus, this assay would be a useful tool for clinical decision-making in determining the presence of the JAK2 V617F mutation in DNA from patient blood samples. Citation Format: Shuo Shen, Robert Brown, Daniel Kim, Larry Pastor, Andrew Y. Fu, Pushpinder Kaur, Alisha Babu, Wei Liu, Aiguo Zhang, Hiromi Tanaka, Michael Y. Sha. A novel XNA technology-based assay to detect JAK2 V617F mutation by real-time PCR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7295.

Using the OPAL data accumulated in 1991–1993 amounting to 74 pb−1 of integrated luminosity, corresponding to 1.64×106 selected multi-hadronic events, a search has been performed for charged particles with unusual mass or unusual charge. The mass was determined from a combination of momentum and ionization energy loss measurements. No isolation criteria were applied to the tracks examined, so that both isolated particles and particles produced in jets were valid candidates. For particles with chargeQ/e=−1, one candidate with a mass of approximately 4.2 GeV/c2 was found, which is compatible with the background rate expected according to a Monte Carlo simulation. The implications of this search for the mass limits of a conjectured stable or quasi-stable charged gluino composite $$(\tilde gq\bar q')^ \pm $$ are discussed. Limits are also presented for the production of fractionally-charged particles withQ/e=±2/3 and ±4/3 as well as for particles withQ/e=±2.

Three jet events are selected from hadronic Z0 decays with a symmetry such that the two lower energy jets are produced with the same energy and in the same jet environment. In some of the events, a displaced secondary vertex is reconstructed in one of the two lower energy jets, which permits the other lower energy jet to be identified as a gluon jet, with an estimated purity of about 93%. Comparing these gluon jets to the inclusive sample of lower energy jets from the symmetric data set yields direct, model independent measurements of quark and gluon jet properties, which have essentially no bias except from the jet definition. Results are reported using both thek ⊥ and cone jet definitions. For thek ⊥ algorithm, we find $$\frac{{\left\langle {n_{k_ \bot }^{ch.} } \right\rangle gluon}}{{\left\langle {n_{k_ \bot }^{ch.} } \right\rangle quark}} = 1.25 \pm 0.02(stat.) \pm 0.03(syst.)$$ for the ratio of the mean charged particle multiplicity of gluon to quark jets, while for the cone algorithm, we find $$\frac{{\left\langle {n_{cone}^{ch.} } \right\rangle gluon}}{{\left\langle {n_{cone}^{ch.} } \right\rangle quark}} = 1.10 \pm 0.02(stat.) \pm 0.02(syst.)$$ using a cone size of 30°. We also report measurements of the angular distributions of particle energy and multiplicity around the jet directions, and of the fragmentation functions of the jets. Gluon jets are found to be substantially broader and to have a markedly softer fragmentation function than quark jets, in agreement with our earlier observations.

This paper presents updated measurements of the lifetimes of the Bs0 meson and the Λb0 baryon using 4.4 million hadronic Z0 decays recorded by the OPAL detector at LEP from 1990 to 1995. A sample of Bs0 decays is obtained using Ds−ℓ+ combinations, where the Ds− is fully reconstructed in the φπ−, K∗0K− and K−K0S decay channels and partially reconstructed in the φℓ−ν̄X decay mode. A sample of Λb0 decays is obtained using Λc+ℓ− combinations, where the Λc+ is fully reconstructed in its decay to a pK−π+ final state and partially reconstructed in the Λℓ+νX decay channel. From 172±28 Ds−ℓ+ combinations attributed to Bs0 decays, the measured lifetime is τ(Bs0)=1.50+0.16−0.15±0.04ps, where the errors are statistical and systematic, respectively. From the 129±25 Λc+ℓ− combinations attributed to Λb0 decays, the measured lifetime is τ(Λb0)=1.29+0.24−0.22±0.06ps, where the errors are statistical and systematic, respectively.

A search for decays of the Bc meson was performed using data collected from 1990–1995 with the OPAL detector on or near the Z0 peak at LEP. The decay channels Bc+→J/ψπ+, Bc+→J/ψa1+ and Bc+→J/ψℓ+ν were investigated, where ℓ denotes an electron or a muon. Two candidates are observed in the mode Bc+→J/ψπ+, with an estimated background of (0.63±0.20) events. The weighted mean of the masses of the two candidates is (6.32±0.06) GeV/c2, which is consistent with the predicted mass of the Bc meson. One candidate event is observed in the mode Bc+→J/ψℓ+ν, with an estimated background of (0.82±0.19) events. No candidate events are observed in the Bc+→J/ψa1+ decay mode, with an estimated background of (1.10±0.22) events. Upper bounds at the 90% confidence level are set on the production rates for these processes.

In this paper an investigation of the production of D∗± mesons produced in e+e− collisions at energies around the Z0 pole is presented. Based on 115D∗± mesons with xD∗ 2ED∗/Ecm> 0.2 the properties of D∗ mesons produced in the reaction Z0→ cc are studied. Fixing the yield and the fragmentation function of bottom quarks to the values obtained at LEP using lepton tags, and average energy fraction of the D∗± mesons from primary charmed quarks of 〈xc→D∗〉 = 0.52 ± 0.03 +- 0.01 is found and Γz0→cc= (323 ± 61 ± 35)MeV is determined. The first error is the combined statistical and systematic error from this experiment, and the second the total error from other sources.

A search has been performed for the production of neutralinos (χ, χ′) in e+e− annihilation at energies near the Z0 pole. No evidence for these particles was found either in searches for events with two acoplanar jets, low visible energy, and missing pt (sensitive to Z0→χχ′→χχff) or in searches for single-photon events (sensitive to Z0→χχ′→χχγ). Model independent upper limits (at the 95% CL) on the branching ratio for the decay mode Z0 →χχ′ of a few 10−4 are obtained for most of the range of neutralino masses that is kinematically accessible at LEP energies. Upper limits on the mixing factor of neutralinos are also placed as a function of the neutralino masses.

Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of 91.2, and 183-209 GeV with the OPAL detector at LEP. The unbiased jets are defined by hemispheres of inclusive hadronic events, while the biased jet measurements are based on three-jet events selected with jet algorithms. Several methods are employed to extract the fragmentation functions over a wide range of scales. Possible biases are studied in the results are obtained. The fragmentation functions are compared to results from lower energy e+e- experiments and with earlier LEP measurements and are found to be consistent. Scaling violations are observed and are found to be stronger for the fragmentation functions of gluon jets than for those of quarks. The measured fragmentation functions are compared to three recent theoretical next-to-leading order calculations and to the predictions of three Monte Carlo event generators. While the Monte Carlo models are in good agreement with the data, the theoretical predictions fail to describe the full set of results, in particular the b and gluon jet measurements.

In an experiment in the CERN-SPS charged-hyperon beam, the main Ω− decay branching ratios have been measured to be Γ(Ω−→ΛK−/Γ(all)=0.686±0.013, Γ(Ω−1→Ξ0π−)/Γ(all)=0.234±0.013, Γ(Ω −→Ξ−π0)/Γ(all)=0.080±0.008. The relative branching ratio of the two Ξπ modes provides a test of the ΔI=12 rule in decuplet-octet transitions. A search has also been made for the rare decay modes Ω−→Λπ−, Ω−→Ξ−γ, Ω−→Ξ−π+π− and Ω −→Ξ0e−ν.

A search is performed for Higgs bosons decaying into invisible final states, produced in association with a Z0 boson in e+e− collisions at energies between 183 and 209 GeV. The search is based on data samples collected by the OPAL detector at LEP corresponding to an integrated luminosity of about 660 pb−1. The analysis aims to select events containing the hadronic decay products of the Z0 boson and large missing momentum, as expected from Higgs boson decay into a pair of stable weakly interacting neutral particles, such as the lightest neutralino in the Minimal Supersymmetric Standard Model. The same analysis is applied to a search for nearly invisible Higgs boson cascade decays into stable weakly interacting neutral particles. No excess over the expected background from Standard Model processes is observed. Limits on the production of invisibly decaying Higgs bosons produced in association with a Z0 boson are derived. Assuming a branching ratio BR(h0→invisible)=1, a lower limit of 108.2 GeV is placed on the Higgs boson mass at the 95% confidence level. Limits on the production of nearly invisibly decaying Higgs bosons are also obtained.

A search for scalar particles and neutralinos such as those predicted by supersymmetric models has been performed using a data sample of 4.4 million hadronic Z0 decays recorded by the OPAL detector at the e+e− collider LEP. The production of such particles typically leads to event topologies consisting of an acoplanar pair of jets, or of a mono-jet, accompanied by sizeable missing energy owing to neutrinos and other undetectable neutral particles. Limits are obtained, at the 95% confidence level, on the masses and production rates of scalar particles produced in association with the Z0. Limits are also placed on neutralino production, for which an additional possible signature is also studied, events containing a single observed photon. Within the Minimal Supersymmetric Standard Model, the mass of the lightest neutralino is found to be larger than 12.5 GeV/c2 at 95% C.L., provided that tan β is larger than 1.5.

The results of a study of charm meson production in semileptonic B hadron decays are presented. Based on a sample of 1.72 million hadronic Z0 decays the following product branching ratios (averaged over electrons and muons) are obtained: $$\begin{gathered} B(b \to D^ + \ell X) \cdot B(D^ + \to K^ - \pi ^ + \pi ^ + ) \hfill \\ = (1.82 \pm 0.20 \pm 0.12) \times 10^{ - 3} , \hfill \\ B(b \to D^0 \ell X) \cdot B(D^0 \to K^ - \pi ^ + ) \hfill \\ = (2.52 \pm 0.14 \pm 0.17) \times 10^{ - 3} \hfill \\ B(b \to D^* \ell X) \cdot B(D^{* + } \to D^0 \pi ^ + ) \cdot B(D^0 \to K^ - \pi ^ + ) \hfill \\ = (7.53 \pm 0.47 \pm 0.56) \times 10^{ - 4} \hfill \\ \end{gathered} $$ where the first error is statistical and the second systematic. The results of a search for the narrow P-wave charmed mesons, (D J ), in semileptonic B decays are also reported. Using the decay channels D 0 →D+π−, D 0 →D*+π− and D + →D0π+ we observe a total signal of 44±8 −7 +3 D 0 and 48±10 −6 +3 D + events. This is the first evidence for semileptonic B decays to charged P-wave charm states. The observed signals also provide evidence for the production of both pseudovector and tensor P-wave charmed mesons in semileptonic B decay. Together these modes are estimated to make up 34±7% of charmed semileptonic B0 and B+ decays.

We report a study of forward-backward multiplicity correlations and a measurement of the dependence on charged multiplicity of the mean transverse momentum of charged hadrons, measured with respect to the thrust axis. The study was performed on a high statistics sample of Z0 decays to multihadronic final states collected by the OPAL Collaboration at LEP. The positive forward-backward multiplicity correlation observed in our inclusive sample can be understood in terms of a superposition of distinct event topologies characterized by a different amount of hard gluon radiation (2-, 3- and 4-jet events) and with different mean multiplicities. The residual positive correlation that we see in a clean 2-jet sample can be interpreted in terms of fragmentation properties of different quark flavours and of the production and decay of resonances. We have compared the observed effects with the predictions of QCD-based parton shower models. The data are well described by the Jetset 7.3 Monte Carlo, while Herwig 5.5 does not satisfactorily reproduce the measured correlations. Hard gluon radiation is also shown to be responsible for the observed increase of about 40% in the mean transverse momentum of produced charged hadrons in the multiplicity range from 10 to 30. The comparison with the results obtained in an analysis of a sample enriched in Z0 → bb̄ events, shows that the presence of heavy flavours does not contribute significantly to the observed effect.

The fragmentation function for the process e+e−→h+X, whereh represents a hadron, may be decomposed into transverse, longitudinal and asymmetric contributions by analysis of the distribution of polar production angles. A number of new tests of QCD have been proposed using these fragmentation functions, but so far no data have been published on the separate components. We have performed such a separation using data on charged particles from hadronic Z0 decays atOpal, and have compared the results with the predictions of QCD. By integrating the fragmentation functions, we determine the average charged particle multiplicity to be $$\overline {n_{ch} } = 21.05 \pm 0.20$$ . The longitudinal to total cross-section ratio is determined to be σ L /σ tot =0.057±0.005. From the longitudinal fragmentation function we are able to extract the gluon fragmentation function. The connection between the asymmetry fragmentation function and electroweak asymmetrics is discussed.

A search for events with photon pairs of large invariant mass is described based on a data sample of 43 pb−1 collected with the OPAL detector. This search is motivated by the L3 observation of four events of the type e+e− → l+l−γγ with an invariant mass of the two photons, mγγ, clustering around 60 GeV. In the OPAL data, four ℓ+ℓ−γγ events are found with mγγ above 40 GeV. The number of observed events is consistent with the QED expectation and no obvious resonance structure is seen. Three candidate qq̄γγ events with mγγ above 40 GeV are found and no νν&#x0304;nγγ candidate with mγγ > 5 GeV is found. From these searches an upper limit is set on any anomalous production of ℓ+ℓ−γγ (ℓ = e, μ, τ) events, where the ℓ+ℓ− pair comes from a virtual Z0 and mγγ is near 60 GeV , of B(Z0 → Z∗0γγ → ℓ+ℓ−γγ) < 6.0 × 10−7 at the 95% CL. In a similar search in the reaction e+e− → γγγ, seven events are observed with a photon pairing of mass near 60 GeV compared to an expected background of 2.7 ± 0.4 from QED. In a search for the production of a 60 GeV resonance X in two-photon collisions, an upper limit is set on ΓXB2(X → γγ) of 2.6 MeV at the 95% CL. A search is also performed for ℓ+ℓ−X (ℓ = e, μ) events in non-γγ decay modes of X. No indication of a 60 GeV resonance is seen. Combining these two searches, ΓX values greater than 110 MeV are excluded at the 95% CL for ℓ+ℓ−γγ (ℓ = e, μ) cross-sections greater than 0.05 pb.