L. Moroni

The pion form factor has been measured in the space-like q2 region 0.014 to 0.26 (GeV/c)2 by scattering 300 GeV pions from the electrons of a liquid hydrogen target. A detailed description is given of the apparatus, data analysis and corrections to the data. The mean square charge radius extracted from the data is model-dependent. We find that a form which includes a realistic description of the form factor phase gives a similar results to the naive pole form, and conclude 〈r2π〉 = 0.438±0.008 fm2.

We report a measurement of the negative pion electromagnetic form factor in the range of space-like four-momentum transfer 0.014 < q2 < 0.122 (GeV/c)2. The measurement was made by the NA7 collaboration at the CERN SPS, by observing the interaction of 300 GeV pions with the electrons of a liquid hydrogen target. The form factor is fitted by a pole form with a pion radius of 〈r2〈12 = 0.657 ± 0.012 fm.

The narrow dip observed at 1.9 GeV/c2 by the Fermilab experiment E687 in diffractive photoproduction of 3π+3π− is examined. The E687 data are refitted, a mechanism is proposed to explain why this resonance appears as a dip, and possible interpretations are discussed.

The magnetic spectrometer and charged particle tracking system used in Fermilab experiment 687 to study the photoproduction and decay of charm particles are described in detail. The photons are produced by a wideband electron beam which can operate at energies up to 600 GeV/c. The spectrometer consists of a high resolution silicon microstrip detector, a large aperture dipole magnet, proportional chambers, a second large aperture dipole, and more proportional chambers. Three multi-cell threshold Cherenkov counters provide charged particle identification. The tracking system is capable of resolving the secondary decay vertices of charm and beauty mesons and baryons from the primary interaction vertex. It also determines the invariant mass of the multibody final states of particles containing heavy quarks with excellent resolution. The particle identification system allows one to identify kaons and protons present in these final states clearly. This collection of detectors produces very clean signals for charm particles and permits one to make many cross checks of the apparatus. The performance is illustrated for a variety of charm signals. Of particular interest is a description of the tracking through the silicon microstrip detector and its use in isolating downstream decay vertices. Two complementary approaches to the reconstruction of secondary decay vertices are presented and insight is gained by comparing their strengths and weaknesses.

Using data from the FOCUS experiment we analyze the D+π− and D0π+ invariant mass distributions. We measure the D2∗0 mass MD2∗0=(2464.5±1.1±1.9)MeV/c2 and width ΓD2∗0=(38.7±5.3±2.9)MeV/c2, and the D2∗+ mass MD2∗+=(2467.6±1.5±0.76)MeV/c2 and width ΓD2∗+=(34.1±6.5±4.2)MeV/c2. We find evidence for broad structures over background in both the neutral and charged final state. If each is interpreted as evidence for a single L=1, jq=1/2 excited charm meson resonance, the masses and widths are M1/20=(2407±21±35)MeV/c2, Γ1/20=(240±55±59)MeV/c2, and M1/2+=(2403±14±35)MeV/c2, Γ1/2+=(283±24±34)MeV/c2, respectively.

Chiral symmetry and its spontaneous breaking play an important role both in the light hadron and heavy hadron systems. The chiral perturbation theory (χPT) is the low energy effective field theory of the Quantum Chromodynamics. In this work, we shall review the investigations on the chiral corrections to the properties of the heavy mesons and baryons within the framework of χPT. We will also review the scatterings of the light pseudoscalar mesons and heavy hadrons, through which many new resonances such as the Ds0∗(2317) could be understood.Moreover, many new hadron states were observed experimentally in the past decades. A large group of these states is near-threshold resonances, such as the charged charmoniumlike Zc and Zcs states, bottomoniumlike Zb states, hidden-charm pentaquark Pc and Pcs states and the doubly charmed Tcc state, etc. They are very good candidates of the loosely bound molecular states composed of a pair of charmed (bottom) hadrons, which are very similar to the loosely bound deuteron. The modern nuclear force was built upon the chiral effective field theory (χEFT), which is the extension of the χPT to the systems with two matter fields. The long-range and medium-long-range interactions between two nucleons arise from the single- and double-pion exchange respectively, which are well constrained by the chiral symmetry and its spontaneous breaking. The short-distance interactions can be described by the low energy constants. Such a framework works very well for the nucleon–nucleon scattering and nuclei. In this work, we will perform an extensive review of the progress on the heavy hadronic molecular states within the framework of χEFT. We shall emphasize that the same chiral dynamics not only govern the nuclei and forms the deuteron, but also dictates the shallow bound states or resonances composed of two heavy hadrons.

The EM form factor of the pion has been studied in the time-like region by measuring σ(e+e− → π+π−) normalized to σ(e+e− → μ+μ−). Results have been obtained for q2 down to the physical threshold.

We have performed a search for CPT violation in neutral charm meson oscillations. While flavor mixing in the charm sector is predicted to be small by the Standard Model, it is still possible to investigate CPT violation through a study of the proper time dependence of a CPT asymmetry in right-sign decay rates for D0→K−π+ and D0→K+π−. This asymmetry is related to the CPT violating complex parameter ξ and the mixing parameters x and y: ACPT∝(Reξ)y−(Imξ)x. Our 95% confidence level limit is −0.0068<(Reξ)y−(Imξ)x<0.0234. Within the framework of the Standard Model Extension incorporating general CPT violation, we also find 95% confidence level limits for the expressions involving coefficients of Lorentz violation of (−2.8<N(x,y,δ)(Δa0+0.6ΔaZ)<4.8)×10−16 GeV, (−7.0<N(x,y,δ)ΔaX<3.8)×10−16 GeV, and (−7.0<N(x,y,δ)ΔaY<3.8)×10−16 GeV, where N(x,y,δ) is the factor which incorporates mixing parameters x, y and the doubly Cabibbo-suppressed to Cabibbo-favored relative strong phase δ.

Progress in experimental particle physics in the coming decade depends crucially upon the ability to carry out experiments in high-radiation areas. In order to perform these complex and expensive experiments, new radiation hard technologies must be developed. This paper discusses the use of diamond detectors in future tracking applications and their survivability in the highest radiation environments. We present results of devices constructed with the newest polycrystalline and single crystal Chemical Vapor Deposition diamond and their tolerance to radiation.

Using a high statistics sample of photoproduced charm particles from the FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between CP even and CP odd final states. These measurements bear on the phenomenology of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074.

Using a large sample of charm semileptonic decays collected by the FOCUS photoproduction experiment at Fermilab, we present evidence for a small, even spin K−π+ amplitude that interferes with the dominant K̄∗0 component in the D+→K−π+μ+ν final state. Although this interference significantly distorts the D+→K−π+μ+ν decay angular distributions, the new amplitude creates only a very small distortion to the observed kaon pion mass distribution when integrated over the other kinematic variables describing the decay. Our data can be described by K̄∗0 interference with either a constant amplitude or broad spin zero resonance.

Analysis of three D → Kππ Dalitz plots is presented using data collected by the Fermilab high energy photoproduction experiment E687. Our data are fit to a model consisting of a sum of Breit-Wigner amplitudes for the intermediate two-body resonant decay modes and a constant term for the nonresonant contribution. We extract branching fractions and relative phases and compare them to the results obtained in other experiments. Although this model qualitatively reproduces many features of our data, statistically significant discrepancies are observed in some of our fits.

FOCUS results from Dalitz plot analyses of D+s and D+ to π+π−π+ are presented. The K-matrix formalism is applied to charm decays for the first time, which allows us to fully exploit the already existing knowledge coming from light-meson spectroscopy experiments. In particular all the measured dynamics of the S-wave ππ scattering, characterized by broad/overlapping resonances and large non-resonant background, can be properly included. This Letter studies the extent to which the K-matrix approach is able to reproduce the observed Dalitz plot and thus help us to understand the underlying dynamics. The results are discussed along with their possible implications for the controversial σ meson.

We describe the algorithm used to identify charged tracks in the fixed-target charm-photoproduction experiment FOCUS.

Using a large sample of D0→K−μ+ν and D0→π−μ+ν decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of the q2 dependence for the f+(q2) form factor. These measured f+(q2) form factors are fit to common parameterizations such as the pole dominance form and compared to recent unquenched Lattice QCD calculations. We find mpole=1.93±0.05±0.03GeV/c2 for D0→K−μ+ν and mpole=1.91−0.15+0.30±0.07GeV/c2 for D0→π−μ+ν and f−(K)(0)/f+(K)(0)=−1.7−1.4+1.5±0.3.

Using data collected by the high-energy photoproduction experiment FOCUS at Fermilab we performed a Dalitz plot analysis of the Cabibbo favored decay D+→K−π+π+. This study uses 53653 Dalitz-plot events with a signal fraction of ∼97%, and represents the highest statistics, most complete Dalitz plot analysis for this channel. Results are presented and discussed using two different formalisms. The first is a simple sum of Breit–Wigner functions with freely fitted masses and widths. It is the model traditionally adopted and serves as comparison with the already published analyses. The second uses a K-matrix approach for the dominant S-wave, in which the parameters are fixed by first fitting Kπ scattering data and continued to threshold by Chiral Perturbation Theory. We show that the Dalitz plot distribution for this decay is consistent with the assumption of two-body dominance of the final state interactions and the description of these interactions is in agreement with other data on the Kπ final state.

Fermilab high-energy photoproduction experiment E687 provides a high statistics sample of the decay mode D+ → K∗0μ+ν (charge conjugates are implied). Our analysis yields a branching ratio of Γ (D+ → K∗0μ+ν)Γ (D+ → K−π+π+) = 0.56±0.04±0.06. The ratios of the form factors governing the decay are measured to be Rν = 1.74 ±0.27±0.28 and R2 = 0.78±0.18±0.10, implying a polarization of ΓlΓt = 1.20±0.13 ±0.13 for the electron decay. Finally, we report new limits on the decay modes D+ → K−π+μ+ν (nonresonent) and D+ → K∗0π0μ+ν.

An observation of an excited ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+\mathrm{*}}$ baryon decaying to ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+}$${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, with ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+}$\ensuremath{\rightarrow}${\mathit{pK}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$, is presented. We reconstruct 39.7\ifmmode\pm\else\textpm\fi{}8.7${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+\mathrm{*}}$ baryons with a mass of 340.4\ifmmode\pm\else\textpm\fi{}0.6\ifmmode\pm\else\textpm\fi{}0.3 MeV/${\mathit{c}}^{2}$ above the ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+}$ mass. The upper limit on the resonant branching ratio is B(${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+\mathrm{*}}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Sigma}}}_{\mathit{c}}$${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$)/B(${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+\mathrm{*}}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+}$ ${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$)36% at the 90% confidence level.

Charmed meson pairs have been photoproduced coherently on an active silicon target. Ninety-eight decays have been analyzed and the lifetime of charged D's has been measured.

Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the K−π+ S-wave amplitude from the decay D+→K−π+π+. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit–Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the K−π+ system.

A narrow dip structure has been observed at 1.9 GeV/c2 in a study of diffractive photoproduction of the 3π+3π− final state performed by the Fermilab experiment E687.

Amplitude analyses of the D+ and Ds+ → K+K−π+ Dalitz plots are presented using data collected by the Fermilab high energy photoproduction experiment E687. Our data are fit to a model consisting of a sum of Breit-Wigner amplitudes for the intermediate two-body resonant decay modes. We extract decay fractions and relative phases. These results are used to infer new branching ratios for D+ → K+K−π+ inclusive as well as the Φπ+ and K∗(892)0K+ channels.

Chemical vapor deposition diamond has been discussed extensively as an alternate sensor material for use very close to the interaction region of the LHC where extreme radiation conditions exist. During the last few years diamond devices have been manufactured and tested with LHC electronics with the goal of creating a detector usable by all LHC experiment. Extensive progress on diamond quality, on the development of diamond trackers and on radiation hardness studies has been made. Transforming the technology to the LHC specific requirements is now underway. In this paper we present the recent progress achieved.

Measurements of elastic photoproduction cross sections for the J/ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.

An amplitude analysis of the D+, Ds+ → π−π+π+ Dalitz plots is presented using data collected by the Fermilab high-energy photoproduction experiment E687. The data are fitted to a model consisting of a sum of relativistic Breit-Wigner amplitudes for the intermediate two-body resonant decay modes plus a flat non-resonant contribution. From the fit we derive decay fractions and relative phases. We also present measurements of Γ(D+→π−π+π+)Γ(D+→K−π+π+) and Γ(Ds+→π−π+π+)Γ(Ds+→K−K+π+).

Using data from the FOCUS (E831) experiment, we have searched for T violation in charm meson decays using the four-body decay channels $D^0 \to K^-K^+\pi^-\pi^+$, $D^+ \to K^0_SK^+\pi^-\pi^+$, and $D^+_s \to K^0_SK^+\pi^-\pi^+$. The T violation asymmetry is obtained using triple-product correlations and assuming the validity of the CPT theorem. We find the asymmetry values to be $A_Tviol (D^0) = 0.010 \pm 0.057(stat.) \pm 0.037(syst.)$, $A_Tviol (D^+) = 0.023 \pm 0.062(stat.) \pm 0.022(syst.)$, and $A_Tviol (D^+_s) = -0.036 \pm 0.067(stat.) \pm 0.023(syst.)$. Each measurement is consistent with no T violation. New measurements of the CP asymmetries for some of these decay modes are also presented.

Using a large sample of D+ to K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of two semileptonic form factor ratios: rv and r2. We find rv = 1.504 \pm 0.057 \pm 0.039 and r2 = 0.875 \pm 0.049 \pm 0.064. Our form factor results include the effects of the s-wave interference discussed in a previous paper.

The ϱ− radiative decay width has been measured by studying the production of ϱ− via the Primakoff effect by 200 GeV incident π− on Cu and Pb targets. This width was obtained by fitting the measured dσ/dt for ϱ production with the theoretical coherent differential cross section including both the electromagnetic and strong contributions. The measured radiative width value is 81 ± 4 ± 4 keV: it is consistent with the ratio Γ(ϱ → πγ)/Γ(ω → πγ) ∼ case:19 as expected from the vector dominance and the quark model.

We present a Kπ mass spectrum analysis of the four-body semileptonic charm decay D+→K−π+μ+ν in the range of 0.65GeV/c2<mKπ<1.5GeV/c2. We observe a non-resonant contribution of 5.30±0.74−0.96+0.99% with respect to the total D+→K−π+μ+ν decay. For the K∗(892)0 resonance, we obtain a mass of 895.41±0.32−0.43+0.35MeV/c2, a width of 47.79±0.86−1.06+1.32MeV/c2, and a Blatt–Weisskopf damping factor parameter of 3.96±0.54−0.90+1.31GeV−1. We also report 90% CL upper limits of 4% and 0.64% for the branching ratios Γ(D+→K¯∗(1680)0μ+ν)Γ(D+→K−π+μ+ν) and Γ(D+→K¯0∗(1430)0μ+ν)Γ(D+→K−π+μ+ν), respectively.

We describe a silicon microstrip detector interleaved with segments of a beryllium oxide target which was used in the FOCUS photoproduction experiment at Fermilab. The detector was designed to improve the vertex resolution and to enhance the reconstruction efficiency of short-lived charm particles.

We present an analysis of the decay D0→K+π− based on FOCUS data. From a sample of 234 signal events, we find a branching ratio of Γ(D0→K+π−)Γ(D0→K−π+)=(0.429−0.061+0.063±0.027)% under the assumptions of no mixing and no CP violation. Allowing for CP violation, we find a branching ratio of (0.429±0.063±0.028)% and a CP asymmetry of 0.18±0.14±0.04. The branching ratio for the case of mixing with no CP violation is (0.381−0.163+0.167±0.092)%. We also present limits on charm mixing.

An all silicon pixel telescope has been assembled and used at the Fermilab Test Beam Facility (FTBF) since 2009 to provide precise tracking information for different test beam experiments with a wide range of Detectors Under Test (DUTs) requiring high resolution measurement of the track impact point. The telescope is based on CMS pixel modules left over from the CMS forward pixel production. Eight planes are arranged to achieve a resolution of less than 8 μm on the 120 GeV proton beam transverse coordinate at the DUT position. In order to achieve such resolution with 100×150 μm2 pixel cells, the planes were tilted to 25 degrees to maximize charge sharing between pixels. Crucial for obtaining this performance is the alignment software, called Monicelli, specifically designed and optimized for this system. This paper will describe the telescope hardware, the data acquisition system and the alignment software constituting this particle tracking system for test beam users.

The paper reviews measurements of the radiation tolerance of CVD diamond for irradiation with 24 GeV/c protons, 300 MeV/c pions and 1 MeV neutrons. For proton and neutron irradiation, the measured charge signal spectrum is compared with the spectrum calculated by a model. Irradiation by particles causes radiation damage leading to a decrease of the charge signal. However, both the measurements and the outcome from the model shows that for tracker applications this drawback is at least partly counterbalanced by a narrowing of the distribution curve of the charge signal. In addition, we observed after proton irradiation at the charge signal spectrum a decrease of the number of small signals. As a result, the efficiency of a CVD diamond tracker is less affected by irradiation than the mean charge signal.

Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the K−π+ S-wave amplitude from the decay D+→K−π+π+. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit–Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the K−π+ system.

A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D+-->K(S)pi+ and D+-->K(S)K+. We have measured the following asymmetry parameters relative to D+-->K-pi+pi+: A(CP)(K(S)pi+) = (-1.6+/-1.5+/-0.9)%, A(CP)(K(S)K+) = (+6.9+/-6.0+/-1.5)%, and A(CP)(K(S)K+) = (+7.1+/-6.1+/-1.2)% relative to D+-->K(S)pi+. We have also measured the relative branching ratios and found Gamma(D+-->K(0)pi+)/Gamma(D+-->K-pi+pi+) = (30.60+/-0.46+/-0.32)%, Gamma(D+-->K(0)K+)/Gamma(D+-->K-pi+pi+) = (6.04+/-0.35+/-0.30)%, and Gamma(D+-->K(0)K+)/Gamma(D+-->K(0)pi+) = (19.96+/-1.19+/-0.96)%.

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement for the branching ratios of the Cabibbo-suppressed decay modes D0→π−π+ and D0→K−K+. We measured: Γ(D0→K−K+)/Γ(D0→π−π+)=2.81±0.10(stat)±0.06(syst), Γ(D0→K−K+)/Γ(D0→K−π+)=0.0993±0.0014(stat)±0.0014(syst), and Γ(D0→π−π+)/Γ(D0→K−π+)=0.0353±0.0012(stat)±0.0006(syst). These values have been combined with other experimental data to extract the ratios of isospin amplitudes and the phase shifts for the D→KK and D→ππ decay channels.

We review genetic programming principles, their application to FOCUS data samples, and use the method to study the doubly Cabibbo suppressed decay D+ -> K+ pi+ pi- relative to its Cabibbo favored counterpart, D+ -> K- pi+ pi+. We find that this technique is able to improve upon more traditional analysis methods. To our knowledge, this is the first application of the genetic programming technique to High Energy Physics data.

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter αΛc in Λc+→Λπ+ decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter A≡αΛc+αΛ¯cαΛc−αΛ¯c. We obtain αΛc=−0.78±0.16±0.19 and A=−0.07±0.19±0.24 where errors are statistical and systematic.

A high statistics sample of photoproduced charm particles from the FOCUS (E831) experiment at Fermilab has been used to search for CP violation in the Cabibbo suppressed decay modes D+→K−K+π+, D0→K−K+ and D0→π−π+. We have measured the following CP asymmetry parameters: ACP(K−K+π+)=+0.006±0.011±0.005, ACP(K−K+)=−0.001±0.022±0.015 and ACP(π−π+)=+0.048±0.039±0.025 where the first error is statistical and the second error is systematic. These asymmetries are consistent with zero with smaller errors than previous measurements.

We present evidence for the Ωc0 in a new decay mode Ωc0 → Σ+K−K−π+, for which we find 42.5 ± 8.8 events with a mass of 2699.9 ± 1.5 ± 2.5 MeV/c2. The data are from Fermilab high energy photoproduction experiment E687.

We report the measurement of masses and widths of the following L=1 charm mesons by the E687 Collaboration at Fermilab: a ${\mathit{D}}_{2}^{\mathrm{*}0}$ state of mass (width) 2453\ifmmode\pm\else\textpm\fi{}3\ifmmode\pm\else\textpm\fi{}2 (25\ifmmode\pm\else\textpm\fi{}10\ifmmode\pm\else\textpm\fi{}5) MeV/${\mathit{c}}^{2}$ decaying to ${\mathit{D}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, a ${\mathit{D}}_{2}^{\mathrm{*}+}$ state of mass (width) 2453\ifmmode\pm\else\textpm\fi{}3\ifmmode\pm\else\textpm\fi{}2 (23\ifmmode\pm\else\textpm\fi{}9\ifmmode\pm\else\textpm\fi{}5) MeV/${\mathit{c}}^{2}$ decaying to ${\mathit{D}}^{0}$${\mathrm{\ensuremath{\pi}}}^{+}$, a ${\mathit{D}}_{1}^{0}$ state of mass (width) 2422\ifmmode\pm\else\textpm\fi{}2\ifmmode\pm\else\textpm\fi{}2 (15\ifmmode\pm\else\textpm\fi{}8\ifmmode\pm\else\textpm\fi{}4) MeV/${\mathit{c}}^{2}$ decaying to ${\mathit{D}}^{\mathrm{*}+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, and a ${\mathit{D}}_{\mathit{s}1}^{+}$ state of mass 2535.0\ifmmode\pm\else\textpm\fi{}0.6\ifmmode\pm\else\textpm\fi{}1.0 MeV/${\mathit{c}}^{2}$ and width 3.2 MeV/${\mathit{c}}^{2}$ at 90% confidence level, decaying to ${\mathit{D}}^{\mathrm{*}+}$${\mathit{K}}_{\mathit{s}}^{0}$ and ${\mathit{D}}^{\mathrm{*}0}$${\mathit{K}}^{+}$.

We report evidence of a narrow resonance at a mass of 2705.9 ± 3.3 ± 2.0 MeV/c2 in the final state Ω−π+ and the charge conjugate. The mass and width support the interpretation of a weakly decaying doubly strange charmed baryon, the Ωc0. Limits on the relative branching ratios for Ωc0→Ω−K−π+π+ and Ωc0→Ω−π−π+π+ are also presented.

We report on the study of charm baryons decaying to Λc+: Λc★+(2625) → Λc+π+π−, Λc★+(2593) → Λc+π+π−, Σc0 → Λc+π− and Σc++ → Λc+π+. We present a confirmation of the state Λc∗+ (2593) and determine its mass difference to be M(Λc★+(2593)) − M(Λc+) = 309.2 ± 0.7 ± 0.3 MeV/c2. We determine the lower limit on the resonant branching ratio to be BR(Λc★+(2593) → Σcπ±Λc★+(2593) → Λc+π+π−) > 0.51 (90% c.l.). We also measure the mass differences M(Σc0) − M(Λc+) = 166.6±0.5±0.6 MeV/c2 and M(Σc++) − M(Λc+) = 167.6±0.6±0.6 MeV/c2. Finally, we measure the relative photoproduction cross sections for Λc★+ and Σc with respect to the (inclusive) photoproduction cross section for Λc+.

We describe the various techniques developed in the Fermilab Wideband Experiments, E687 and FOCUS, to reconstruct long-lived states. The techniques all involve modifications to standard tracking techniques and are useful to report for future experiments.

The paper gives new results on the radiation tolerance of CVD diamond for irradiation with 300 MeV/c pions and 24 GeV/c protons. The measured charge signal spectrum is compared at several irradiation levels with the spectrum calculated by a model. Irradiation by particles causes damage leading to a decrease of the charge signal. However, both the measurements and the outcome from the model show that for tracker applications this drawback is at least partly counterbalanced by a narrowing of the distribution curve of the charge signal. As a result, the efficiency of a CVD diamond tracker is less affected by irradiation than the mean charge signal.

Chemical Vapor Deposited (CVD) polycrystalline diamond has been proposed as a radiation-hard alternative to silicon in the extreme radiation levels occurring close to the interaction region of the Large Hadron Collider. Due to an intense research effort, reliable high-quality polycrystalline CVD diamond detectors, with up to 270μm charge collection distance and good spatial uniformity, are now available. The most recent progress on the diamond quality, on the development of diamond trackers and on radiation hardness studies are presented and discussed.

We report measurements of charm particle production asymmetries from the Fermilab photoproduction experiment E687. An asymmetry in the rate of production of charm versus anticharm particles is expected to arise primarily from fragmentation effects. We observe statistically significant asymmetries in the photoproduction of D+, D∗+ and D0 mesons and find small (but statistically weak) asymmetries in the production of the Ds+ meson and the Λc+ baryon. Our inclusive photoproduction asymmetries are compared to predictions from nonperturbative models of charm quark fragmentation.

Using data from the FOCUS (E831) experiment at Fermilab, we present new measurements for the Cabibbo-suppressed decay mode D 0 → π -π + π -π + .We measure the branching ratio0022.An amplitude analysis has been performed, a first for this channel, in order to determine the resonant substructure of this decay mode.The dominant component is the decay D 0 → a 1 (1260) + π -, accounting for 60% of the decay rate.The second most dominant contribution comes from the decay D 0 → ρ(770) 0 ρ(770) 0 , with a fraction of 25%.We also study the a 1 (1260) line shape and resonant substructure.Using the helicity formalism for the angular distribution of the decay D 0 → ρ(770) 0 ρ(770) 0 , we measure a longitudinal polarization of P L = (71 ± 4 ± 2)%.

Coherent 3π production on nine different nuclear targets has been studied using a 40 GeV/c π− beam at the Serpukhov accelerator (CERN-Serpukhov experiment no. 5). The absorption in nuclear matter of the produced system has been measured, analysing the data on the different nuclear targets. Identica results are obtained from the differential cross sections and from the coherent nuclear cross sections. The 1+ waves show a very weak absorption, definitely smaller than 0− and 2− waves. No influence on the absorption comes from the spin-flip amplitudes, which have been found to be negligible in the coherent region.

Using a high statistics sample of photo-produced charm particles from the FOCUS experiment at Fermilab, we report results of a search for eight rare and Standard-Model-forbidden decays: D+, Ds+ > h+/- muon-/+ muon+ (with h=pion or Kaon). Improvement over previous results by a factor of 1.7--14 is realized. Our branching ratio upper limit D+ > pion+ muon- muon+ of 8.8E-6 at the 90% C.L. is below the current MSSM R-Parity violating constraint.

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement for the Cabibbo-suppressed decay mode D0→K+K−π+π−. We measure: Γ(D0→K+K−π+π−)/Γ(D0→K−π−π+π+)=0.0295±0.0011±0.0008. An amplitude analysis has been performed in order to determine the resonant substructure of this decay mode. The dominant components are the decays D0→K1(1270)+K−, D0→K1(1400)+K− and D0→ρ(770)0ϕ(1020).

Using a high statistics sample of photo-produced charm particles from the FOCUS experiment at Fermilab, we report on the measurement of the ratio of semileptonic rates \Gamma(D+ > ANTI-K pi mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.625 +/- 0.045 +/- 0.034. Allowing for the K pi S-wave interference measured previously by FOCUS, we extract the vector to pseudoscalar ratio \Gamma(D+ > ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.594 +/- 0.043 +/- 0.033 and the ratio \Gamma(D+ > ANTI-K0 mu+ nu)/\Gamma(D+ > K- pi+ pi+)= 1.019 +/- 0.076 +/- 0.065. Our results show a lower ratio for \Gamma(D > K* \ell nu})/\Gamma(D > K \ell nu) than has been reported recently and indicate the current world average branching fractions for the decays D+ >ANTI-K0(mu+, e+) nu are low. Using the PDG world average for B(D+ > K- pi+ pi+) we extract B(D+ > ANIT-K0 mu+ nu)=(9.27 +/- 0.69 +/- 0.59 +/- 0.61)%.

We present a search for a charmed pentaquark decaying strongly to D(∗)−p. Finding no evidence for such a state, we set limits on the cross-section times branching ratio relative to D∗− and D− under particular assumptions about the production mechanism.

Using a large sample of D+ -> K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first measurements of the helicity basis form factors free from the assumption of spectroscopic pole dominance. We also present the first information on the form factor that controls the s-wave interference discussed in a previous paper by the FOCUS collaboration. We find reasonable agreement with the usual assumption of spectroscopic pole dominance and measured form factor ratios.

We present a search for a pentaquark decaying strongly to pKS0 in γN collisions at a center-of-mass energy up to 25 GeV. Finding no evidence for such a state in the mass range of 1470MeV/c2 to 2200MeV/c2, we set limits on the yield and on the cross section times branching ratio relative to Σ∗(1385)± and K∗(892)+.

Test beam results obtained with 3D pixel sensors bump-bonded to the RD53A prototype readout ASIC are reported. Sensors from FBK Italy and IMB-CNM (Spain) have been tested before and after proton-irradiation to an equivalent fluence of about 1 × 1016 ≠cm-2 (1 MeV equivalent neutrons). This is the first time that one single collecting electrode fine pitch 3D sensors are irradiated up to such fluence bump-bonded to a fine pitch ASIC. The preliminary analysis of the collected data shows no degradation on the hit detection efficiencies of the tested sensors after high energy proton irradiation, demonstrating the excellent radiation tolerance of the 3D pixel sensors. Thus, they will be excellent candidates for the extreme radiation environment at the innermost layers of the HL-LHC experiments.

We present the first measurement of the lifetime of the Ωc0 baryon. The data were collected in the Fermilab high energy photoproduction experiment E687. The measured lifetime is τ = 86−20+27(stat.) ± 28(syst.) fr. Thus the Ωc0 has one of the shorter lifetimes among the weakly decaying singly charmed baryons.

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

We present precision measurements of the D0 and D+ meson lifetimes using approximately 7500 fully reconstructed D0→K−π+, K−π+π+π−, D+→K−π+π+, and charge conjugate decays. The data were accumulated by the Fermilab high ene rgy photoproduction experiment E687. The lifetime of the D0 is measured to be 0.424±0.011±0.007 ps while the D+ lifetime is measured to be 1.075±0.040±0.018 ps.

Using data collected by the fixed target Fermilab experiment FOCUS, we present several first measurements for the semileptonic decay D0→K¯0π−μ+ν. Using a model that includes a K¯0π− s-wave component, we measure the form factor ratios to be rv=1.71±0.68±0.34 and r2=0.91±0.37±0.10 and the s-wave amplitude to be A=0.35±0.22±0.05GeV−1. Finally, we measure the vector semileptonic branching ratio Γ(D0→K*(892)−μ+ν)Γ(D0→K¯0π−π+)=0.337±0.034±0.013.

Fermilab high-energy photoproduction experiment E687 measures a branching ratio of Γ (DS+ → φμ+ν) /Γ (DS+ → φμ+) = 0.58 ± 0.17 (stat) ± 0.07 (sys). This branching ratio is combined with theoretical inputs to obtain a new measurement of the DS+ absolute branching ratio of Γ (DS+ → φμ+) / Γ (DS+ → all) = 0.031 ± 0.009 (stat 0.005 (sys) ± 0.004 (theoretical).

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

A high statistics sample of photoproduced charm particles from the FOCUS (E831) experiment at Fermilab has been used to measure the D0 and D+ lifetimes. Using about 210000 D0 and 110000 D+ events we obtained the following values: 409.6±1.1 (statistical)±1.5 (systematic) fs for D0 and 1039.4±4.3 (statistical)±7.0 (systematic) fs for D+.

CVD diamond detectors are of interest for charged particle detection and tracking due to their high radiation tolerance. In this article, we present, for the first time, beam test results from recently manufactured CVD diamond strip detectors and their behavior under low doses of electrons from a β-source and the performance before and after intense (>1015/cm2) proton- and pion-irradiations. We find that low dose irradiation increase the signal-to-noise ratio (pumping of the signal) and slightly deteriorate the spatial resolution. Intense irradiation with protons 2.2×1015p/cm2 lowers the signal-to-noise ratio slightly. Intense irradiation with pions 2.9×1015π/cm2 lowers the signal-to-noise ratio more. The spatial resolution of the diamond sensors improves after irradiations.

Using a large sample of Ds to Phi mu nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of two semileptonic form factor ratios: rV and r2. We find rV = 1.549 \pm 0.250 \pm 0.145 and r2 = 0.713 \pm 0.202 \pm 0.266. These values are consistent with the rV and r2 form factors measured for the process D+ to K*bar mu nu.

We present a new measurement of the branching ratio of the Cabibbo suppressed decay D^0\to \pi^-\mu^+\nu relative to the Cabibbo favored decay D^0\to K^-\mu^+\nu and an improved measurement of the ratio |\frac{f_+^{\pi}(0)}{f_+^{K}(0)}|. Our results are 0.074 \pm 0.008 \pm 0.007 for the branching ratio and 0.85 \pm 0.04 \pm 0.04 \pm 0.01 for the form factor ratio, respectively.

Abstract Diamond sensors are studied as an alternative to silicon sensors to withstand the high radiation doses that are expected in future upgrades of the pixel detectors for the SLHC. Diamond pixel sensors are intrinsically radiation hard and are considered as a possible solution for the innermost tracker layers close to the interaction point where current silicon sensors cannot cope with the harsh radiation environment.An effort to study possible candidates for the upgrades is undergoing using the Fermilab test-beam facility (FTBF), where diamonds and 3D silicon sensors have been studied. Using a CMS pixel-based telescope built and installed at the FTBF, we are studying charge collection efficiencies for un-irradiated and irradiated devices bump-bonded to the CMS PSI46 pixel readout chip. A description of the test-beam effort and preliminary results on diamond sensors will be presented.

We irradiated two diamond detectors with 62 MeV energy proton beam up to an integrated fluence of about 2×1015 protons/cm2 at INFN-LNS in Catania (Italy). The detectors were made of two high purity poly-crystal diamond sensors. The electric contacts of the two diamond sensors were from different sources and made with different techniques: a proprietary DLC/Pt/Au electric contact and our own novel UV Laser technique. We collected 120 GeV and 62 MeV proton beam data, before and after irradiation, respectively, to extract the radiation damage constant of one poly-crystal diamond sensor by using single crystal diamond detector response as reference.

Results obtained with 3D columnar pixel sensors bump-bonded to the RD53A prototype readout chip are reported. The interconnected modules have been tested in a hadron beam before and after irradiation to a fluence of about 1×1016 neq cm−2 (1 MeV equivalent neutrons). All presented results are part of the CMS R&D activities in view of the pixel detector upgrade for the High Luminosity phase of the LHC at CERN (HL-LHC) . A preliminary analysis of the collected data shows hit detection efficiencies around 97% measured after proton irradiation.

Studies of the decay D0 → K−μ+νμ are reported by Fermilab photoproduction experiment E687. The ratio BR(D0→ K−μ+νμ)BR(D0→ K−π+) is determined to be 0.852 ± 0.034 (statistical) ± 0.028 (systematic). Using this result and an isospin argument we infer the ratio BR(D0→ K∗−μ+νμ)BR(D0→ K−μ+νμ)= 0.62 ± 0.07 ± 0.09. The pole mass from the single pole form factor is measured to be Mpole = 1.87−0.08−0.06+0.11+0.07 GeV/c2. Using Mpole and BR(D0→ K−μ+νμ)BR(D0→ K−π+), we calculate |f + (0)| = 0.71 ± 0.03 ± 0.03. We also measure the ratio f − (0)f + (0)= −1.3−3.4+3.6± 0.6.

We report on the results of a search for fourteen flavor changing neutral current, lepton number violating, or lepton family number violating decays of the charmed meson D+ in the large charm sample recorded by the Fermilab photoproduction experiment E687. No evidence is seen for these rare and standard-model-forbidden decays, of the form D+ → h±ℓ∓ℓ+ (with h = π, K and ℓ = e, μ); we determine 90% confidence level upper limits on their absolute branching fractions in the range (9–20) × 10−5.

We report precise measurements of the D0 and D+ meson lifetimes by the E687 Collaboration at Fermilab. The measurements have been made using 16000 fully reconstructed decays of the D0 into the K−π+ and K−π+π−π+ final states and 9000 decays of the D+ into the K−π+π+ final state. The lifetimes of the D0 and D+ mesons are measured to be 0.413±0.004±0.003 ps and 1.048±0.015±01011 ps respectively.

A precise determination of the charm-strange baryon Cascade(c)+ lifetime is presented. The data were accumulated by the Fermilab high-energy photoproduction experiment FOCUS. The measurement is made with 300 Cascade(c)+ --> Cascade- pi+ pi+ decays, 130 Cascade(c)+ --> Sigma+ K- pi+ decays, 45 Cascade(c)+ --> p K- pi+ decays and 58 Cascade(c)+ --> Lambda K- pi+ pi+ decays. The Cascade(c)+ lifetime is measured to be 0.439+/-0.022+/-0.009 ps.

The first observation of neutral pion production in πe inelastic scattering is presented. The cross section at 300 GeV for |t‖>62;10−3 (GeV / c)2 is 2.11 ± 0.47 nb, in good agreement with the theory of PCAC anomalies with 3 quark colours.

We present the first clear observation of the doubly Cabibbo suppressed decay D+→K−K+K+ and the first observation of the singly Cabibbo suppressed decay Ds+→K−K+K+. These signals have been obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS (E831) experiment at Fermilab. We measure the following relative branching ratios: Γ(D+→K−K+K+)/Γ(D+→K−π+π+)=(9.49±2.17±0.22)×10−4 and Γ(Ds+→K−K+K+)/Γ(Ds+→K−K+π+)=(8.95±2.12+2.24−2.31)×10−3, where the first error is statistical and the second is systematic.

Using the FOCUS spectrometer with photon beam energies between 20 and 160 \gev, we confirm the existence of a diffractively photoproduced enhancement in $K^+K^-$ at 1750 \mevcc with nearly 100 times the statistics of previous experiments. Assuming this enhancement to be a single resonance with a Breit-Wigner mass shape, we determine its mass to be $1753.5\pm 1.5\pm 2.3$ \mevcc and its width to be $122.2\pm 6.2\pm 8.0$ \mevcc. We find no corresponding enhancement at 1750 \mevcc in $K^*K$, and again neglecting any possible interference effects we place limits on the ratio $\Gamma (X(1750) \to K^*K)/\Gamma (X(1750) \to K^+K^-)$. Our results are consistent with previous photoproduction experiments, but, because of the much greater statistics, challenge the common interpretation of this enhancement as the $\phi (1680)$ seen in $e^+e^-$ annihilation experiments.

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.

An improved target for lifetime measurements of short living particles has been implemented and tested along with the data processing electronics. The target is intended for measurements of lifetimes in the 10-13s region. In order to reduce the granularity and to make the measurement of such a short lifetime feasible, special techniques have been adopted to decrease the capacitance of the detectors and to improve the performance of signal processing electronics.

Using data collected by the high energy photoproduction experiment FOCUS at Fermilab we study the doubly and singly Cabibbo suppressed decays D+ and Ds+ --> K+ pi+ pi-. Branching ratios and Dalitz plot analyses are performed.

Using data collected by the fixed target Fermilab experiment FOCUS, we measure the branching ratios of the Cabibbo-favored decays Ξc+→Σ+K−π+, Ξc+→Σ+K̄∗(892)0, and Ξc+→Λ0K−π+π+ relative to Ξc+→Ξ−π+π+ to be 0.91±0.11±0.04, 0.78±0.16±0.06, and 0.28±0.06±0.06, respectively. We report the first observation of the Cabibbo-suppressed decay Ξc+→Σ+K+K− and we measure the branching ratio relative to Ξc+→Σ+K−π+ to be 0.16±0.06±0.01. We also set 90% confidence level upper limits for Ξc+→Σ+φ and Ξc+→Ξ∗(1690)0(Σ+K−)K+ relative to Ξc+→Σ+K−π+ to be 0.12 and 0.05, respectively. We find an indication of the decays Ξc+→Ω−K+π+ and Ξc+→Σ∗(1385)+K̄0 and set 90% confidence level upper limits for the branching ratios with respect to Ξc+→Ξ−π+π+ to be 0.12 and 1.72, respectively. Finally, we determine the 90% C.L. upper limit for the resonant contribution Ξc+→Ξ∗(1530)0π+ relative to Ξc+→Ξ−π+π+ to be 0.10.

We apply a genetic programming technique to search for the doubly Cabibbo suppressed decays Λc+→pK+π− and Ds+→K+K+π−. We normalize these decays to their Cabibbo favored partners and find BR(Λc+→pK+π−)/BR(Λc+→pK−π+)=(0.05±0.26±0.02)% and BR(Ds+→K+K+π−)/BR(Ds+→K−K+π+)=(0.52±0.17±0.11)% where the first errors are statistical and the second are systematic. Expressed as 90% confidence levels (CL), we find <0.46 and <0.78%, respectively. This is the first successful use of genetic programming in a high energy physics data analysis.

Abstract Traditionally, completion equipment has been run in clear fluids, brines, or base oils, to minimize the potential for solids to plug equipment, preventing tools from being set correctly or setting prematurely. However, both brines and base oils have limitations. Base oils typically have densities around 0.8 sg which has well control implications and brines can become prohibitively expensive where high densities are required. In the North Sea, many wells are either highly deviated or require extended reach to access compartmentalised reservoirs. Consequently, the reservoir often comprises a significant proportion of shales. The use of brine as a completion fluid can therefore lead to significant wellbore instability and reservoir impairment issues. A novel approach has been employed by a UK operator to address these problems by compromising between the shale stability provided by oil and the density achievable with brine. The fluid employed is a low-solids, invert emulsion formulated with a high-density internal phase brine. Due to the density limit of the base solids-free brine, additional density is achieved through the use of manganese tetraoxide (Mn3O4). Manganese tetraoxide has a very small, sub-micron, particle size which allows a degree of self suspension thus allowing a fluid with low viscosities to be utilized. The use of this type of formulation provides a fluid which gives good wellbore stability while running completions screens but allows the completion fluid to be produced back in the testing phase of the well without plugging the screens due to the extremely fine particle size of the manganese tetraoxide. This fluid was designed to exhibit excellent sag performance while minimizing the gellation potential of the fluid. The physical characteristics of manganese tetraoxide (small spherical particles) were an important factor in the design of the fluid due to the very tight clearances expected when setting downhole tools. This paper presents laboratory design data and case histories from the UK sector of the North Sea and in Kazakhstan where this type of high-density fluid has been used to run the lower completions while successfully maintaining wellbore stability.

Abstract An increasing number of wells are being drilled in formations with a high risk of well bore instability. Historically, the majority of instability was a result of drilling reactive clays with water-based fluids. This is still a common risk and is usually addressed by using oil- and synthetic-based fluids. However, we now more commonly have to overcome the problems associated with drilling depleted or weak formations which can be difficult to drill even with oil- or synthetic fluids. This is especially common in fields that have been producing for many years and where geological pressures have been altered. More and more often, stress caging techniques are being used to drill these unstable formations. Effective stress caging is relatively straight forward if all the parameters are known; however, this is rarely the case and accurate fracture and pore throat measurement in-situ is nearly impossible. To seal these fractures, which are sometimes a few microns or less, a new form of micro- or nano-sized sealant is required in addition to the conventional calcium carbonate/graphite particle blend. This paper presents a novel drilling fluid additive that utilises particles of approximately 200nm to seal fractures and pores to stop the invasion of drilling fluid filtrate and reduce pore pressure transmission. This enables wells to be drilled in depleted formations without losses, use very high overbalances with no differential sticking, and also plug micro pores and micro fractures found in shales to reduce instability and improve hole integrity. Laboratory testing is described that demonstrates the advantages of using this technology and case histories proving its usefulness in the field are described. Utilisation of this new nanotechnology will enable many problematic formations to be drilled safely and trouble-free by reducing the risk of wellbore failure.

Due to the large expected instantaneous luminosity, the future HL-LHC upgrade sets strong requirements on the radiation hardness of the CMS detector Inner Tracker. Sensors based on 3D pixel technology, with its superior radiation tolerance, comply with these extreme conditions. A full study and characterization of pixelated 3D sensors fabricated by FBK is presented here. The sensors were bump-bonded to RD53A readout chips and measured at several CERN SPS test beams. Results on charge collection and efficiency, for both non-irradiated and irradiated up to 1016 neq/cm2 samples, are presented. Two main studies are described: in the first the behaviour of the sensor is qualified as a function of irradiation, while kept under identical conditions; in the second the response is measured under typical operating conditions.

A precise measurement of the ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$ meson lifetime is reported. The data were accumulated by the high energy photoproduction experiment E687 at Fermilab in the 1990--1991 fixed target run. The measurement has been done using 900 fully reconstructed ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$\ensuremath{\rightarrow}\ensuremath{\varphi}${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$ decays. The lifetime of the ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$ meson is measured to be 0.475\ifmmode\pm\else\textpm\fi{}0.020\ifmmode\pm\else\textpm\fi{}0.007 ps.

Measurements of the mass and lifetime of the ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{+}$ decaying into ${\mathrm{\ensuremath{\Xi}}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{+}$ are presented. The data were accumulated by the Fermilab high-energy photoproduction experiment E687. The mass of the ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{+}$ is measured to be 2464.4\ifmmode\pm\else\textpm\fi{}2.0\ifmmode\pm\else\textpm\fi{}1.4 MeV/${\mathit{c}}^{2}$ and the lifetime is measured to be 0.${41}_{\mathrm{\ensuremath{-}}0.08}^{+0.11}$\ifmmode\pm\else\textpm\fi{}0.02 ps.

The fermilab high-energy photoproduction experiment E687 provides a sample of approximately 90 events of the decay mode D+s→ φμ+ ν. The ratios of the form factors governing the decay are measured to be Rv=1.8±0.9±0.2 and R2= 1.1±0.8±0.1, implying a polarization of Г1/Гt = 1.0±0.5±0.1 for the electron decay, consistent with our measurement of the form factor for the decay D+ → K∗0 μ+ ν.

A measurement of the lifetime of the charmed strange baryon ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{0}$ is presented. The data were accumulated by the Fermilab high energy photoproduction experiment E687. The measurement has been made using 42\ifmmode\pm\else\textpm\fi{}10 ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Xi}}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$ decays. The lifetime of the ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{0}$ is measured to be 0.${101}_{\mathrm{\ensuremath{-}}0.017}^{+0.025}$\ifmmode\pm\else\textpm\fi{}0.005 ps and its mass is measured to be 2462.1\ifmmode\pm\else\textpm\fi{}3.1\ifmmode\pm\else\textpm\fi{}1.4 MeV/${\mathit{c}}^{2}$.

CVD diamond material was used to build position-sensitive detectors for single-charged particles to be employed in high-intensity physics experiments. To obtain position information, metal contacts shaped as strips or pixels are applied to the detector surface for one- or two-dimensional coordinate measurement. Strip detectors 2×4 cm2 in size with a strip distance of 50 μm were tested. Pixel detectors of various pixel sizes were bump bonded to electronics chips and investigated. A key issue for the use of these sensors in high intensity experiments is the radiation hardness. Several irradiation experiments were carried out with pions, protons and neutrons exceeding a fluence of 1015 particles/cm2. The paper presents an overview of the results obtained with strip and pixel detectors in high-energy test beams and summarises the irradiation studies.

The FOCUS experiment (FNAL-E831) has used two channels, Ω−π+ and Ξ−K−π+π+, to measure the lifetime of the Ωc0 charmed baryon. From a sample of 64±14 signal events at a mass of 2.698 GeV/c2, we measure an Ωc0 lifetime of 72±11 (stat.) ±11 (sys.) fs, substantially improving upon the current world average.

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the branching ratio for the Cabibbo-favored decay mode D0→K−K−K+π+. From a sample of 143±19 fully reconstructed D0→K−K−K+π+ events, we measure Γ(D0→K−K−K+π+)/Γ(D0→K−π−π+π+)=0.00257±0.00034(stat.)±0.00024(syst.). A coherent amplitude analysis has been performed to determine the resonant substructure of this decay mode. This analysis reveals a dominant contribution from φ and K∗0(892) states.

The High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) calls for new high radiation-tolerant solid-state pixel sensors, capable of surviving irradiation fluences up to a few 1016 neq/cm2 at ∼3 cm from the interaction point. The INFN ATLAS-CMS joint research activity, in collaboration with Fondazione Bruno Kessler, is aiming at the development of thin n+ on p type pixel sensors to be operated at the HL-LHC. The R&D covers both planar and 3D pixel devices made on substrates obtained by the Direct Wafer Bonding technique. The active thickness of the planar sensors studied in this paper is 100μm or 130μm, that of 3D sensors 130μm. First prototypes of hybrid modules, bump-bonded to the present CMS readout chips (PSI46 digital), have been characterized in beam tests. First results on their performance before and after irradiation up to a maximum fluence of ∼5×1015 neq/cm2 are reported in this article.

Charged hadronic four-body decays of D0 mesons have been studied in the E687 photoproduction experiment at Fermilab. Branching ratios relative to the D0 → K−π+π+π− decay mode for the Cabibbo-suppressed decays D0 → π−π+π−π+, D0 → K−K+π−π+ have been measured and the first evidence of the D0 → K−K+K−π+ decay mode is reported. An analysis of the D0 → K−K+π−π+ resonance structure is also presented.

We report a measurement of the semimuonic decay D0→K−μ+ν from data taken during the 1987–1988 fixed target run at Fermilab by the E687 Collaboration. We obtain Γ(D0→K−μ+ν)/Γ(D0→K−π+)=0.82±0.13±0.13 and use this result to calculate Γ(D0→K∗−μ+ν)/Γ(D0→K−μ+ν)=0.59±0.10±0.13.

Analysis of data from the Fermilab high energy photoproduction experiment E687 for events containing fully and partially reconstructed pairs of charmed mesons is presented. Correlations from DD pairs are used to study production dynamics.

A new GeSi active target is presently used in the NA1 experiment at CERN to study photoproduction of charmed particles and to measure their lifetimes. Some general comments on the active target technique are made.

Using a large sample of charm semileptonic decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of two semileptonic branching ratios. We obtain values of D+ to K*munu/k2pi = 0.602 +/- 0.010 +/- 0.021 and Ds to phimunu/phipi = 0.54 +/- 0.033 +/- 0.048. Our result D+ result includes the effects of s-wave interference.

Studies of DD correlations for a large sample of events containing fully and partially reconstructed pairs of charmed D mesons recorded by the Fermilab photoproduction experiment FOCUS (FNAL-E831) are presented. Correlations between D and D mesons are used to study heavy quark production dynamics. We present results for fully and partially reconstructed charm pairs and comparisons to a recent version of Pythia with default parameter settings. We also comment on the production of ψ(3770) in our data.

Using data from the FOCUS experiment (FNAL-E831), we report on the decay of $D^0$ mesons into final states containing more than one $K^0_S$. We present evidence for two Cabibbo favored decay modes, $D^0\to K^0_SK^0_S K^- \pi^+$ and $D^0\to K^0_SK^0_S K^+ \pi^-$, and measure their combined branching fraction relative to $D^0\to \bar{K} ^0\pi^+\pi^-$ to be $\frac{\Gamma(D^0\to K^0_SK^0_SK^{\pm}\pi^{\mp})}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0106 $\pm$ 0.0019 $\pm$ 0.0010. Further, we report new measurements of $\frac{\Gamma(D^0\to K^0_SK^0_SK^0_S)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0179 $\pm$ 0.0027 $\pm$ 0.0026, $\frac{\Gamma(D^0\to K^0\bar{K} ^0)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0144 $\pm$ 0.0032 $\pm$ 0.0016, and $\frac{\Gamma(D^0\to K^0_SK^0_S\pi^+\pi^-)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0208 $\pm$ 0.0035 $\pm$ 0.0021 where the first error is statistical and the second is systematic.