W. Erdmann

Cross sections for elastic production of J/Psi mesons in photoproduction and electroproduction are measured in electron proton collisions at HERA using an integrated luminosity of 55 pb^{-1}. Results are presented for photon virtualities Q^2 up to 80 GeV^2. The dependence on the photon-proton centre of mass energy W_{gamma p} is analysed in the range 40 < \Wgp < 305 GeV in photoproduction and 40 < \Wgp < 160 GeV in electroproduction. The \Wgp dependences of the cross sections do not change significantly with Q^2 and can be described by models based on perturbative QCD. Within such models, the data show a high sensitivity to the gluon density of the proton in the domain of low Bjorken x and low Q^2. Differential cross sections d\sigma/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range |t|<1.2 GeV^2 as functions of \Wgp and Q^2. Effective Pomeron trajectories are determined for photoproduction and electroproduction. The J/Psi production and decay angular distributions are consistent with s-channel helicity conservation. The ratio of the cross sections for longitudinally and transversely polarised photons is measured as a function of Q^2 and is found to be described by perturbative QCD based models.

A new measurement of the proton structure function F2 (x, Q2) is reported for momentum transfers squared Q2 between ].5 GeV2 and 5000 GeV2 and for Bjorken x between 3 · 10−5 and 0.32 using data collected by the HERA experiment H1 in 1994. The data represent an increase in statistics by a factor of ten with respect to the analysis of the 1993 data. Substantial extension of the kinematic range towards low Q2 and x has been achieved using dedicated data samples and events with initial state photon radiation. The structure function is found to increase significantly with decreasing x, even in the lowest accessible Q2 region. The data are well described by a Next to Leading Order QCD fit and the gluon density is extracted.

A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton (ep) scattering in the kinematic range 8.5 < Q2 < 50GeV2, 2.4 × 10−4 < Bjorken-x < 0.0133, and 3.7 × 10−4 < χp < 0.043. The diffractive contribution to the proton structure function F2(x,Q2) is evaluated as a function of the appropriate deep-inelastic scattering variables χp, Q2, β (= χχp) using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. the dependence of this contribution on χp is measured to be χp−n with n = 1.19 ± 0.06 (stat.) ± 0.07 (syst.) independent of β and Q2, which is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of the Q2 and β dependences of a factorised structure function is presented. For all measured β, this structure function is observed to be consistent with scale invariance.

A measurement of the proton structure function F2(x, Q2) is reported for momentum transfers squared Q2 between 4.5 GeV2 and 1600 GeV2 and for Bjorken x between 1.8 × 10−14 and 0.13 using data collected by the HERA experiment H1 in 1993. It is observed that F2 increases significantly with decreasing x, confirming our previous measurement made with one tenth of the data available in this analysis. The Q2 dependence is approximately logarithmic over the full kinematic range covered. The subsample of deep inelastic events with a large pseudo-rapidity gap in the hadronic energy flow close to the proton remnant is used to measure the “diffractive” contribution to F2.

The cross-section for deeply virtual Compton scattering in the reaction ep→eγp has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb−1 of e+p and 16.7 pb−1 of e−p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the γ∗p system in the region 5<Q2<100 GeV2 and 40<W<140 GeV. The measured cross-sections rise steeply with increasing W. The measurements are compared to QCD-based calculations.

Cross sections for elastic photoproduction of J/ψ and ϒ mesons are presented. For J/ψ mesons the dependence on the photon-proton centre-of-mass energy Wγp is analysed in an extended range with respect to previous measurements of 26≤Wγp≤285GeV. The measured energy dependence is parameterized as σγp∝Wγpδ with δ=0.83±0.07. The differential cross section dσ/dt for J/ψ mesons is derived, its dependence on Wγp and on t is analysed and the effective trajectory (in terms of Regge theory) is determined to be α(t)=(1.27±0.05)+(0.08±0.17)·t/GeV2. Models based on perturbative QCD and on pomeron exchange are compared to the data.

A measurement is presented of elastic deeply virtual Compton scattering e++p→e++γ+p at HERA using data taken with the H1 detector. The cross section is measured as a function of the photon virtuality, Q2, and the invariant mass, W, of the γp system, in the kinematic range 2<Q2<20GeV2, 30<W<120GeV and |t|<1GeV2, where t is the squared momentum transfer to the proton. The measurement is compared to QCD based calculations.

A narrow resonance in D∗−p and D∗+p̄ invariant mass combinations is observed in inelastic electron–proton collisions at centre-of-mass energies of 300 GeV and 320 GeV at HERA. The resonance has a mass of 3099±3(stat.)±5(syst.) MeV and a measured Gaussian width of 12±3(stat.) MeV, compatible with the experimental resolution. The resonance is interpreted as an anti-charmed baryon with a minimal constituent quark composition of uuddc̄, together with the charge conjugate.

The readout chip for the CMS pixel detector has to deal with an enormous data rate. On-chip zero suppression is inevitable and hit data must be buffered locally during the latency of the first level trigger. Dead-time must be kept at a minimum. It is dominated by contributions coming from the readout. To keep it low an analog readout scheme has been adopted where pixel addresses are analog coded. We present the architecture of the final CMS pixel detector readout chip with special emphasis on the analog readout chain. Measurements of its performance are discussed.

Measurements are presented of inclusive charm and beauty cross sections in e^+p collisions at HERA for values of photon virtuality 12 \le Q^2 \le 60 GeV^2 and of the Bjorken scaling variable 0.0002 \le x \le 0.005. The fractions of events containing charm and beauty quarks are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector. Values for the structure functions F_2^{c\bar{c}} and F_2^{b\bar{b}} are obtained. This is the first measurement of F_2^{b\bar{b}} in this kinematic range. The results are found to be compatible with the predictions of perturbative quantum chromodynamics and withprevious measurements of F_2^{c\bar{c}}.

The design, construction and performance of the H1 silicon vertex detector is described. It consists of two cylindrical layers of double-sided, double-metal silicon sensors read out by a custom designed analog pipeline chip. The analog signals are transmitted by optical fibres to a custom-designed ADC board and are reduced on PowerPC processors. Details of the design and construction are given and performance figures from the first data-taking periods are presented.

A measurement of the derivative (d ln F_2 / d lnx)_(Q^2)= -lambda(x,Q^2) of the proton structure function F_2 is presented in the low x domain of deeply inelastic positron-proton scattering. For 5*10^(-5)<=x<=0.01 and Q^2>=1.5 GeV^2, lambda(x,Q^2) is found to be independent of x and to increase linearly with ln(Q^2).

The inclusive production of D∗±(2010) mesons in deep-inelastic scattering is studied with the H1 detector at HERA. In the kinematic region 1<Q2<100 GeV2 and 0.05<y<0.7 an e+p cross section for inclusive D∗± meson production of 8.50±0.42(stat.)+1.21−1.00(syst.) nb is measured in the visible range ptD∗>1.5 GeV and |ηD∗|<1.5. Single and double differential inclusive D∗± meson cross sections are compared to perturbative QCD calculations in two different evolution schemes. The charm contribution to the proton structure, F2c(x,Q2), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q2=1.5 GeV2 to more than 25% at Q2=60 GeV2 corresponding to x values ranging from 5×10−5 to 3×10−3.

Measurements are presented of inclusive charm and beauty cross sections in e + p collisions at HERA for values of photon virtuality Q 2 > 150 GeV 2 and of inelasticity 0.1 < y < 0.7.The charm and beauty fractions are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector.The data are divided into four regions in Q 2 and Bjorken x, and values for the structure functions F cc 2 and F

First results on inclusive $$\mathop {D^0 }\limits^{( - )} $$ andD*± production in neutral current deep inelasticep scattering are reported using data collected by the H1 experiment at HERA in 1994. Differential cross sections are presented for both channels and are found to agree well with QCD predictions based on the boson gluon fusion process. A charm production cross section for 10 GeV2≤Q2≤100 GeV2 and 0.01≤y≤0.7 of $$\sigma (ep \to ec\bar cX) = (17.4 \pm 1.6 \pm 1.7 \pm 1.4) nb$$ is derived. A first measurement of the charm contribution $$F_2^{c\bar c} (x,Q^2 )$$ to the proton structure function for Bjorkenx between 8·10−4 and 8·10−3 is presented. In this kinematic range a ratio $$F_2^{c\bar c} /F_2 = 0.237 \pm 0.021 \pm 0.041$$ is observed.

A measurement of the inclusive cross section for the deep-inelastic scattering of positrons off protons at HERA is presented at momentum transfers 8.5 ≤ Q2 ≤ 35 GeV2 and large inelasticity <y> = 0.7, i.e. for the Bjorken-x range 0.00013 ≤ x ≤ 0.00055. Using a next-to-leading order QCD fit to the structure function F2 at lower y values, the contribution of F2 to the measured cross section at high y is calculated and, by subtraction, the longitudinal structure function FL is determined for the first time with an average value of FL = 0.52 ± 0.03 (statt)−0.22+0.25 (syst) at Q2 = 15.4 GeV2 and x = 0.000243.

Transverse momentum spectra of charged particles produced in deep inelastic scattering are measured as a function of the kinematic variables x_B and Q2 using the H1 detector at the ep collider HERA. The data are compared to different parton emission models, either with or without ordering of the emissions in transverse momentum. The data provide evidence for a relatively large amount of parton radiation between the current and the remnant systems.

Results on diffractive photoproduction of ψ(2S) mesons are presented using data collected between 1996 and 2000 with the H1 detector at the HERA ep collider. The data correspond to an integrated luminosity of 77 pb−1. The energy dependence of the diffractive ψ(2S) cross section is found to be similar to or possibly somewhat steeper than that for J/ψ mesons. The dependences of the elastic and proton dissociative ψ(2S) photoproduction cross sections on the squared momentum transfer t at the proton vertex are measured. The t-dependence of the elastic channel, parametrised as ebt, yields belψ(2S)=(4.31±0.57±0.46) GeV−2, compatible with that of the J/ψ. For the proton dissociative channel the result bpdψ(2S)=(0.59±0.13±0.12) GeV−2 is 2.3 standard deviations smaller than that measured for the J/ψ. With proper account of the individual wavefunctions theoretical predictions based on perturbative QCD are found to describe the measurements well.

The elastic electroproduction of φ mesons is studied at HERA with the H1 detector for photon virtualities 1<Q2<15GeV2 and hadronic centre of mass energies 40<W<130 GeV. The Q2 and t dependences of the cross section are extracted (t being the square of the four-momentum transfer to the target proton). When plotted as function of (Q2 + MV2) and scaled by the appropriate SU(5) quark charge factor, the φ meson cross section agrees within errors with the cross sections of the vector mesons V = ρ, ω and J/ψ. A detailed analysis is performed of the φ meson polarisation state and the ratio of the production cross sections for longitudinally and transversely polarised φ mesons is determined. A small but significant violation of s-channel helicity conservation (SCHC) is observed.

The production of transverse energy in deep inelastic scattering is measured as a function of the kinematic variables $x$ and $Q^2$ using the H1 detector at the ep collider HERA. The results are compared to the different predictions based upon two alternative QCD evolution equations, namely the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) and the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equations. In a pseudorapidity interval which is central in the hadronic centre of mass system between the current and the proton remnant fragmentation region the produced transverse energy increases with decreasing $x$ for constant $Q^2$. Such a behaviour can be explained with a QCD calculation based upon the BFKL ansatz. The rate of forward jets, proposed as a signature for BFKL dynamics, has been measured.

The cross section for the elastic photoproduction of ϱ0 mesons (γp → ϱ0p) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the ϱ0 decay giving a cross section of 9.1 ± 0.9 (stat.) ± 2.5 (syst.) μb. The logarithmic slope parameter of the differential cross section, dσ/dt, is found to be 10.9 ± 2.4 (stat.) ± 1.1 (syst.) GeV−2. The ϱ0 decay polar angular distribution is found to be consistent with s-channel helicity conservation. The higher energy cross section was determined from analysis of the lower part of the hadronic invariant mass spectrum of diffractive photoproduction and found to be 13.6 ± 0.8 (stat.) ± 2.4 (syst.) μb.

Inclusive production cross sections are measured in deep inelastic scattering at HERA for meson states composed of a charm quark and a light antiquark or the charge conjugate.The measurements cover the kinematic region of photon virtuality 2 < Q 2 < 100 GeV 2 , inelasticity 0.05 < y < 0.7, D meson transverse momenta p t (D) ≥ 2.5 GeV and pseudorapidity |η(D)| ≤ 1.5.The identification of the D-meson decays and the reduction of the combinatorial background profit from the reconstruction of displaced secondary vertices by means of the H1 silicon vertex detector.The production of charmed mesons containing the light quarks u, d and s is found to be compatible with a description in which the hard scattering is followed by a factorisable and universal hadronisation process.

The pixel detector is the innermost tracking device of the CMS experiment at the LHC. It is built from two independent subdevices, the pixel barrel and the end disks. The barrel consists of three concentric layers around the beam pipe with mean radii of 4.4, 7.3 and 10.2 cm. There are two end disks on each side of the interaction point at ±34.5 and ±46.5cm. This article gives an overview of the pixel barrel detector, its mechanical support structure, electronics components, services and its expected performance.

The total cross sections for the elastic electroproduction of P and Jψ mesons for Q2 > 8 GeV2 and 〈W〉 ⋍ 90 GeV/c2 are measured at HERA with the H1 detector. The measurements are for an integrated electron-proton luminosity of ⋍3 pb−1. The dependences of the total virtual photon-proton (γ∗p) cross sections on Q2, W and the momentum transfer squared to the proton (t), and, for the ϱ, the dependence on the polar decay angle (cos θ∗ are presented. The Jψ : ∂ cross section ratio is determined. The results are discussed in the light of theoretical models and of the interplay of hard and soft physics processes.

At the electron-proton collider HERA the inclusive D∗± meson photoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where 〈Wγp〉 ≈ 200 GeV and Q2 < 0.01 GeV2, the result is σ(γp → ccX) = (13.2 ± 2.2−1.7 −4.8+2.1 +9.9) μb. The second measurement for Q2 < 4 GeV2 yields σ(γp → ccX) = (9.3 ± 2.1−1.8 −3.2+1.9 +6.9) μb at 〈Wγp〉 ≈ 142 GeV and σ(γp → ccX) = (20.6 ± 5.5−3.9 −7.2+4.3 +15.4 μb at 〈Wγp〉 ≈ 230 GeV, respectively. The third error accounts for an additional uncertainty due to the proton and photon parton density parametrizations. Differential cross sections are presented as a function of the D∗± transverse momentum and rapidity. The results compare reasonably well with next-to-leading order QCD calculations. Evidence for diffractive photoproduction of charm quarks is presented.

We present a QCD analysis of the proton structure function F2 measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of F2 in the range 2 · 10−4 < x < 3 · 10−2 and compared with an approximate solution of the QCD evolution equations. The gluon density is found to rise steeply with decreasing x.

A measurement of the beauty production cross section in ep collisions at a centre-of-mass energy of 319 GeV is presented. The data were collected with the H1 detector at the HERA collider in the years 1999-2000. Events are selected by requiring the presence of jets and muons in the final state. Both the long lifetime and the large mass of b-flavoured hadrons are exploited to identify events containing beauty quarks. Differential cross sections are measured in photoproduction, with photon virtualities Q^2 < 1 GeV^2, and in deep inelastic scattering, where 2 < Q^2 < 100 GeV^2. The results are compared with perturbative QCD calculations to leading and next-to-leading order. The predictions are found to be somewhat lower than the data.

The diffractive photoproduction of J/psi mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb^-1. The differential cross section d sigma(gamma p -> J/psi Y) / d t is studied in the range 2 < |t| < 30 GeV^2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy W in three t intervals, spanning the range 50 < W < 200 GeV. A fast rise of the cross section with W is observed for each t range and the slope for the effective linear Pomeron trajectory is measured to be alpha^\prime= -0.0135 \pm 0.0074 (stat.) \pm 0.0051 (syst.) GeV^-2. The measurements are compared with perturbative QCD models based on BFKL and DGLAP evolution. The data are found to be compatible with s-channel helicity conservation.

A search for single top quark production is performed in e^\pm p collisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb^-1. A model for the anomalous production of top quarks in a flavour changing neutral current process involving a t-u-gamma coupling is investigated. Decays of top quarks into a b quark and a W boson are considered in the leptonic and the hadronic decay channels of the W. Both a cut-based analysis and a multivariate likelihood analysis are performed to discriminate anomalous top quark production from Standard Model background processes. In the leptonic channel, 5 events are found while 1.31 \pm 0.22 events are expected from the Standard Model background. In the hadronic channel, no excess above the expectation for Standard Model processes is found. These observations lead to a cross section \sigma (ep -> e t X) = 0.29 +0.15 -0.14 pb at \sqrt{s} = 319 GeV. Alternatively, assuming that the observed events are due to a statistical fluctuation, upper limits of 0.55 pb on the anomalous top production cross section and of 0.27 on the t-u-gamma coupling \kappa_{t-u-gamma} are established at the 95% confidence level.

Using a simplified Navier-Stokes equation it has been possible to compute the electrodynamic convection generated by a radio frequency coil field for the modern needle-eye float-zone growth of silicon. The calculated electrodynamic force in such a zone shows maximum values up to 11.7 N/cm3 and generates flow velocities between 25 and 100 cm/s. As only superficial convection can be brought about by electrodynamic forces, the axial and radial dopant incorporation will not be influenced strongly. A comparison of electrodynamic forces with the other forces possibly causing flow in silicon floating zones shows that the electrodynamic forces exceed all other forces by several orders of magnitude.

Fette und SeifenVolume 54, Issue 4 p. 197-201 Article Siedepunkte der Fettsäuren Prof. Dr. E. Jantzen, Prof. Dr. E. Jantzen Abteilung für Technische Chemie des Chemischen Staatsinstituts HamburgSearch for more papers by this authorDipl.-Chem. W. Erdmann, Dipl.-Chem. W. Erdmann Abteilung für Technische Chemie des Chemischen Staatsinstituts HamburgSearch for more papers by this author Prof. Dr. E. Jantzen, Prof. Dr. E. Jantzen Abteilung für Technische Chemie des Chemischen Staatsinstituts HamburgSearch for more papers by this authorDipl.-Chem. W. Erdmann, Dipl.-Chem. W. Erdmann Abteilung für Technische Chemie des Chemischen Staatsinstituts HamburgSearch for more papers by this author First published: 1952 https://doi.org/10.1002/lipi.19520540403Citations: 16AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume54, Issue41952Pages 197-201 RelatedInformation

Photoproduction of 2-jet events is studied with the H1 detector at HERA. Parton cross sections are extracted from the data by an unfolding method using leading order parton-jet correlations of a QCD generator. The gluon distribution in the photon is derived in the fractional momentum range 0.04 ⩽ xγ ⩽ 1 at the average factorization scale 75 GeV2.

We present a study of Jψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The Jψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → JψX) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ Wγp ≤ 180 GeV and Q2 ≲ 4 GeV2. Using the flux of quasi-real photons with Q2 ≲ 4 GeV2, a total production cross section of σ(γp → J/ψX) = (56±13±14) nb is derived at an average Wγp=90 GeV. The distribution of the squared momentum transfer t from the proton to the Jψ can be fitted using an exponential exp(−b∥t∥) below a ∥t∥ of 0.75 GeV2 yielding a slope parameter of b = (4.7±1.9) GeV−2.

A search for leptoquarks at HERA was performed in H1 using 1994 e+ p data corresponding to an integrated luminosity of about 3 pb−1. Single leptoquarks were searched for in direct positron-quark fusion processes taking into account possible decays into lepton-quark pairs of either the first, the second, or the third generation. No significant deviation from the Standard Model predictions is found in the various final states studied and mass dependent exclusion limits are derived on the Yukawa couplings of the leptoquarks. Compared with earlier results from an analysis of e− p data, exclusion limits are considerably improved for leptoquarks which could be produced via e+ -valence quark fusion. For leptoquarks with lepton flavour conserving couplings, masses up to 275 GeV (depending on the leptoquark type) are excluded for coupling values larger than 4πλem. For leptoquarks with lepton flavour violating couplings, masses up to 225 GeV are excluded for couplings with leptons of the second or third generation larger than 4πλem. Fourteen possible combinations of couplings are studied and stringent exclusion limits comparable or better than any existing direct or indirect limits are obtained for each leptoquark type.

A model-independent search for deviations from the Standard Model prediction is performed in e+p and e−p collisions at HERA using H1 data corresponding to an integrated luminosity of 117pb−1. For the first time all event topologies involving isolated electrons, photons, muons, neutrinos and jets with high transverse momenta are investigated in a single analysis. Events are assigned to exclusive classes according to their final state. A statistical algorithm is developed to search for deviations from the Standard Model in the distributions of the scalar sum of transverse momenta or invariant mass of final state particles and to quantify their significance. A good agreement with the Standard Model prediction is observed in most of the event classes. The most significant deviation is found for a topology containing an isolated muon, missing transverse momentum and a jet, consistent with a previously reported observation.

A search for events with a high-energy isolated electron or muon and missing transverse momentum has been performed at the electron–proton collider HERA using an integrated luminosity of 13.6 pb−1 in e−p scattering and 104.7 pb−1 in e+p scattering. Within the Standard Model such events are expected to be mainly due to W boson production with subsequent leptonic decay. In e−p interactions one event is observed in the electron channel and none in the muon channel, consistent with the expectation of the Standard Model. In the e+p data a total of 18 events are seen in the electron and muon channels compared to an expectation of 12.4±1.7 dominated by W production (9.4±1.6). Whilst the overall observed number of events is broadly in agreement with the number predicted by the Standard Model, there is an excess of events with transverse momentum of the hadronic system greater than 25 GeV with 10 events found compared to 2.9±0.5 expected. The results are used to determine the cross-section for events with an isolated electron or muon and missing transverse momentum.

The reaction e+p→e+X is studied with the H1 detector at Hera. The data cover momentum transfers Q2 between 200GeV2 and 30000GeV2 and correspond to an integrated luminosity of 35.6pb−1. The differential cross section dσ/dQ2 is compared to the Standard Model expectation for neutral current scattering and analysed to search for (ēe)(q̄q) contact interactions. No evidence for new phenomena is observed. The results are used to set limits on scales within models of electron–quark compositeness, quark form factors and the exchange of virtual heavy leptoquarks. A search for gravitational effects mediated through the exchange of virtual gravitons which propagate into large extra dimensions is presented.

Using the H1 detector at HERA, charged particle multiplicity distributions in deep inelastice + p scattering have been measured over a large kinematical region. The evolution withW andQ 2 of the multiplicity distribution and of the multiplicity moments in pseudorapidity domains of varying size is studied in the current fragmentation region of the hadronic centre-of-mass frame. The results are compared with data from fixed target lepton-nucleon interactions,e + e − annihilations and hadron-hadron collisions as well as with expectations from QCD based parton models. Fits to the Negative Binomial and Lognormal distributions are presented.

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWexLMBb50ujb% qeguuDJXwAKbacfiGaf8hCaaNbaebacqWFWbaCaaa!3DB7! $$\bar pp$$ data and QCD calculations. The comparisons show that theγp events can be consistently described by QCD models including — in addition to the primary hard scattering process — interactions between the two beam remnants. The differential jet cross sectionsdσ/dE T jet anddσ/dη jet are measured.

The readout chip for the CMS pixel detector must handle an enormous flux of data, while keeping the data loss at a minimum. Full size prototype readout chips bump-bonded to sensors have been tested in a pion beam simulating an LHC-like environment, and the data loss as a function of particle fluence has been measured.

A search for scalar and vector leptoquarks coupling to first generation fermions is performed using the e+p and e−p scattering data collected by the H1 experiment between 1994 and 2000. The data correspond to a total integrated luminosity of 117pb−1. No evidence for the direct or indirect production of such particles is found in data samples with a large transverse momentum final state electron or with large missing transverse momentum. Constraints on leptoquark models are established. For leptoquark couplings of electromagnetic strength, leptoquarks with masses up to 275–325GeV are ruled out at 95% confidence level. These limits improve and supercede earlier H1 limits based on subsamples of the data used here.

Dijet production in deep inelastic ep scattering is investigated in the region of low values of the Bjorken-variable x (10 -4 < x < 10 -2 ) and low photon virtualities Q 2 (5 < Q 2 < 100 GeV 2 ).The measured dijet cross sections are compared with perturbative QCD calculations in next-to-leading order.For most dijet variables studied, these calculations can provide a reasonable description of the data over the full phase space region covered, including the region of very low x.However, large discrepancies are observed for events with small separation in azimuth between the two highest transverse momentum jets.This region of phase space is described better by predictions based on the CCFM evolution equation, which incorporates k t factorized unintegrated parton distributions.A reasonable description is also obtained using the Color Dipole Model or models incorporating virtual photon structure.

Events with no hadronic energy flow in a large interval of pseudo-rapidity in the proton direction are observed in photon-proton interactions at an average centre of mass energy 〈√sγp〉 of 200 GeV These events are interpreted as photon diffractive dissociation. Evidence for hard scattering in photon diffractive dissociation is demonstrated using inclusive single particle spectra, thrust as a function of transverse energy, and the observation of jet production. The data can be described by a Monte Carlo calculation including hard photon-pomeron scattering.

A measurement of inclusive jet cross-sections in deep-inelastic ep scattering at HERA is presented based on data with an integrated luminosity of 21.1 pb−1. The measurement is performed for photon virtualities Q2 between 5 and 100 GeV2, differentially in Q2, in the jet transverse energy ET, in ET2/Q2 and in the pseudorapidity ηlab. With the renormalization scale μR=ET, perturbative QCD calculations in next-to-leading order (NLO) give a good description of the data in most of the phase space. Significant discrepancies are observed only for jets in the proton beam direction with ET below 20 GeV and Q2 below 20 GeV2. This corresponds to the region in which NLO corrections are largest and further improvement of the calculations is thus of particular interest.

Using the deep inelastic e^+p and e^-p charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994-2000 and correspond to an integrated luminosity of 117.2 pb^{-1}. A measurement is obtained of the W propagator mass in charged current ep scattering. The weak mixing angle sin^2 theta_W is determined in the on-mass-shell renormalisation scheme. A first measurement at HERA is made of the light quark weak couplings to the Z^0 boson and a possible contribution of right-handed isospin components to the weak couplings is investigated.

The CMS pixel detector is a complex device consisting of about 1400 modules. The control and the readout systems of this detector will be described. The detector modules have to be correctly set up before data taking can start. This means downloading of a very large number of parameters to the front-ends. During data taking the information from the detector has to be read out and various detector parameters have to be monitored. The readout system has to be very efficient to minimize dead time. A set of fast control signals will be used to reset and re-synchronize the detector.

A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*± meson and a muon. The correlation between the D* meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.

Data taken with positrons of different longitudinal polarisation states in collision with unpolarised protons at HERA are used to measure the total cross sections of the charged current process, e^+ p \to \bar{\nu}X, for negative four-momentum transfer squared Q^2 > 400 GeV^2 and inelasticity y<0.9. Together with the corresponding cross section obtained from the previously published unpolarised data, the polarisation dependence of the charged current cross section is measured for the first time at high Q^2 and found to be in agreement with the Standard Model prediction.

Deep-inelastic e±p scattering at high squared momentum transfer Q2 up to 30 000 GeV2 is used to search for eq contact interactions associated to scales far beyond the Hera centre of mass energy. The neutral current cross section measurements dσ/dQ2, corresponding to integrated luminosities of 16.4 pb−1 of e−p data and 100.8 pb−1 of e+p data, are well described by the Standard Model and are analysed to set constraints on new phenomena. For conventional contact interactions lower limits are set on compositeness scales Λ ranging between 1.6–5.5 TeV. Couplings and masses of leptoquarks and squarks in R-parity violating supersymmetry are constrained to M/λ>0.3–1.4 TeV. A search for low scale quantum gravity effects in models with large extra dimensions provides limits on the effective Planck scale of MS>0.8 TeV. A form factor analysis yields a bound on the radius of light quarks of Rq<1.0×10−18 m.

Deep inelastic scattering (DIS) events, selected from 1993 data taken by the H1 experiment at HERA, are studied in the Breit frame of reference. The fragmentation function of the quark is compared with those of \ee data. It is shown that certain aspects of the quarks emerging from within the proton in \ep interactions are essentially the same as those of quarks pair-created from the vacuum in \ee annihilation. The measured area, peak position and widthof the fragmentation function show that the kinematic evolution variable, equivalent to the \ee squared centre of mass energy, is in the Breit frame the invariant square of the four-momentum transfer. We comment on the extent to which we have evidence for coherence effects in parton showers.

Jet rates in deep inelastic electron proton scattering are studied with the H1 detector at HERA for momentum transfers squared between 10 and 4000 GeV2. It is shown that they can be quantitatively described by perturbative QCD in next to leading order making use of the parton densities of the proton and with the strong coupling constant αs as a free parameter. The measured value, αs(MZ2) = 0.123 ± 0.018, is in agreement both with determinations from e+e− annihilation at LEP using the same observable and with the world average.

The Q2 dependence and the total cross sections for charged and neutral current processes are measured in e±p reactions for transverse momenta of the outgoing lepton larger than 25 GeV. Comparable size of cross sections for the neutral current process and for the weak charged current process are observed above Q2 ∥ 5000 GeV2. Using the shape and magnitude of the charged current cross section we determine a propagator mass of mW = 84−7+10 GeV.

Three-jet production is studied for the first time in deep-inelastic positron-proton scattering. The measurement carried out with the H1 detector at HERA covers a large range of four-momentum transfer squared 5 < Q^2 < 5000 GeV^2 and invariant three-jet masses 25 < M_(3jet) < 140 GeV. Jets are defined by the inclusive k_T algorithm in the Breit frame. The size of the three-jet cross section and the ratio of the three-jet to the dijet cross section R_(3/2) are described over the whole phase space by the predictions of perturbative QCD in next-to-leading order. The shapes of angular jet distributions deviate significantly from a uniform population of the available phase space but are well described by the QCD calculation.

A contact interaction analysis is presented to search for new phenomena beyond the Standard Model in deep inelastic $e^\pm p \rightarrow e^\pm \, hadrons$ scattering. The data are collected with the H1 detector at HERA and correspond to integrated luminosities of $0.909 \ {\rm pb}^{-1}$ and $2.947 \ {\rm pb}^{-1}$ for electron and positron beams, respectively. The differential cross sections $d\sigma / dQ^2$ are measured in the $Q^2$ range bet\-ween $160 \ \GeV^2$ and $20,000 \ \GeV^2$. The absence of any significant deviation from the Standard Model prediction is used to constrain the couplings and masses of new leptoquarks and to set limits on electron--quark compositeness scales and on the radius of light quarks.

A search for contributions to the reaction ep→eπ0N∗ from photon–odderon fusion in the photoproduction regime at HERA is reported, at an average photon–proton centre-of-mass energy 〈W〉=215 GeV. The measurement proceeds via detection of the π0 decay photons, a leading neutron from the N∗ decay, and the scattered electron. No π0 signal is observed and an upper limit on the cross section for the photon–odderon fusion process of σ(γp→π0N∗)<49 nb at the 95% confidence level is derived, integrated over the experimentally accessible range of the squared four-momentum transfer at the nucleon vertex 0.02<|t|<0.3 GeV2. This excludes a recent prediction from a calculation based on a non-perturbative QCD model of a photon–odderon fusion cross section above 200 nb.

The helicity structure of the diffractive electroproduction of ρ mesons, e+p→e+ρ+Y, is studied in a previously unexplored region of large four-momentum transfer squared at the proton vertex, t: 0<t′<3 GeV2, where t′=|t|−|t|min. The data used are collected with the H1 detector at HERA in the kinematic domain 2.5<Q2<60 GeV2, 40<W<120 GeV. No t dependence of the r0400 spin density matrix element is found. A significant t dependent helicity non-conservation from the virtual photon to the ρ meson is observed for the spin density matrix element combinations r500+2r511 and r100+2r111. These t dependences are consistently described by a perturbative QCD model based on the exchange of two gluons.

Results are presented on the photoproduction of isolated prompt photons, inclusively and associated with jets, in the γp center of mass energy range 142 < W < 266 GeV.The cross sections are measured for the transverse momentum range of the photons 5 < E γ T < 10 GeV and for associated jets with E jet T > 4.5 GeV.They are measured differentially as a function of E γ T , E jet T , the pseudorapidities η γ and η jet and estimators of the momentum fractions x γ and x p of the incident photon and proton carried by the constituents participating in the hard process.In order to further investigate the underlying dynamics, the angular correlation between the prompt photon and the jet in the transverse plane is studied.Predictions by perturbative QCD calculations in next to leading order are about 30% below the inclusive prompt photon data after corrections for hadronisation and multiple interactions, but are in reasonable agreement with the results for prompt photons associated with jets.Comparisons with the predictions of the event generators PYTHIA and HERWIG are also presented.

Differential dijet cross sections are measured in photoproduction in the region of photon virtualities Q^2 < 1 GeV^2 with the H1 detector at the HERA ep collider using an integrated luminosity of 66.6 pb^{-1}. Jets are defined with the inclusive k_T algorithm and a minimum transverse momentum of the leading jet of 25 GeV is required. Dijet cross sections are measured in direct and resolved photon enhanced regions separately. Longitudinal proton momentum fractions up to 0.7 are reached. The data compare well with predictions from Monte Carlo event generators based on leading order QCD and parton showers and with next-to-leading order QCD calculations corrected for hadronisation effects.

Cross sections for the production of two isolated muons up to high di-muon masses are measured in ep collisions at HERA with the H1 detector in a data sample corresponding to an integrated luminosity of 71 pb−1 at a centre of mass energy of s=319 GeV. The results are in good agreement with Standard Model predictions, the dominant process being photon–photon interactions. Additional muons or electrons are searched for in events with two high transverse momentum muons using the full data sample corresponding to 114 pb−1, where data at s=301 GeV and s=319 GeV are combined. Both the di-lepton sample and the tri-lepton sample agree well with the predictions.

Measurements of K0 meson and Λ baryon production in deep-inelastic positron-proton scattering (DIS) are presented in the kinematic range 10 < Q2 < 70 GeV2 and 10−4 < x < 10−2. The measurements, obtained using the H1 detector at the HEPA collider, are discussed in the light of possible mechanisms for increased strangeness production at low Bjorken-x. Comparisons of the xF spectra, where xF is the fractional longitudinal momentum in the hadronic centre-of-mass frame, are made with results from electron-positron annihilation. The xF spectra and the K0 “seagull” plot are compared with previous DIS results. The mean K0 and Λ multiplicities are studied as a function of the centre-of-mass energy W and are observed to be consistent with a logarithmic increase with W when compared with previous measurements. A comparison of strangeness production in diffractive and non-diffractive DIS is made. An upper limit of 0.9 nb, at the 95% confidence level, is placed on the cross section for QCD instanton induced events.

Inclusive jet cross sections are measured in photoproduction at HERA using the H1 detector. The data sample of e+ p -> e+ + jet + X events in the kinematic range of photon virtualities Q^2 < 1 GeV^2 and photon-proton centre-of-mass energies 95 < W_gammap < 285 GeV represents an integrated luminosity of 24.1 pb^-1. Jets are defined using the inclusive k_T algorithm. Single- and multi-differential cross sections are measured as functions of jet transverse energy E_T^jet and pseudorapidity \eta^jet in the domain 5 < E_T^jet < 75 GeV and -1 < \eta^jet < 2.5. The cross sections are found to be in good agreement with next-to-leading order perturbative QCD calculations corrected for fragmentation and underlying event effects. The cross section differential in E_T^jet, which varies by six orders of magnitude over the measured range, is compared with similar distributions from p pbar colliders at equal and higher energies.

Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and deep inelastic scattering are presented as a function of several kinematic variables. Leading order QCD simulation programs are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are able to describe the data. Next-to-leading order perturbative QCD calculations based on pion exchange are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined. The dijet events with a leading neutron have a lower fraction of resolved photon processes than do the inclusive dijet data.

The diffractive photoproduction of ρ mesons, ep→eρY, with large momentum transfer squared at the proton vertex, |t|, is studied with the H1 detector at HERA using an integrated luminosity of 20.1pb−1. The photon–proton centre of mass energy spans the range 75<W<95GeV, the photon virtuality is restricted to Q2<0.01GeV2 and the mass MY of the proton remnant is below 5 GeV. The t dependence of the cross section is measured for the range 1.5<|t|<10.0GeV2 and is well described by a power law, dσ/d|t|∝|t|−n. The spin density matrix elements, which provide information on the helicity structure of the interaction, are extracted using measurements of angular distributions of the ρ decay products. The data indicate a violation of s-channel helicity conservation, with contributions from both single and double helicity-flip being observed. The results are compared to the predictions of perturbative QCD models.

A search for squarks in R-parity violating supersymmetry is performed in $e^+ p$ collisions at HERA at a centre of mass energy of 300 GeV, using H1 data corresponding to an integrated luminosity of 37 pb $^{-1}$ . The direct production of single squarks of any generation in positron-quark fusion via a Yukawa coupling $\lambda'$ is considered, taking into account R-parity violating and conserving decays of the squarks. No significant deviation from the Standard Model expectation is found. The results are interpreted in terms of constraints within the Minimal Supersymmetric Standard Model (MSSM), the constrained MSSM and the minimal Supergravity model, and their sensitivity to the model parameters is studied in detail. For a Yukawa coupling of electromagnetic strength, squark masses below 260 GeV are excluded at 95% confidence level in a large part of the parameter space. For a 100 times smaller coupling strength masses up to 182 GeV are excluded.

Pixel detectors will be the innermost tracking layers of the CMS experiment. A large Lorentz angle will help to achieve good spatial resolution by interpolation. The first measurement of the Lorentz angle in irradiated silicon sensors is presented. A small pixel assembly using a radiation hard prototype readout chip has been tested with X-rays. The developments for the full readout chip are reviewed and results from SEU measurements with DMILL structures are shown.

The total cross section for the photoproduction process with a leading proton in the final state has been measured at gamma p centre-of-mass energies W of 91, 181 and 231 GeV. The measured cross sections apply to the kinematic range with the transverse momentum of the scattered proton restricted to p_Tproton <= 0.2 GeV and 0.68 <= z <= 0.88, where z = E_p'/E_p is the scattered proton energy normalised to the beam energy. The cross section dsigma_(gamma p -> Xp')(W,z)/dz is observed to be independent of W and z within the measurement errors and amounts to 8.05 +- 0.06 stat +- 0.89 syst mub on average. The data are well described by a Triple Regge model in which the process is mediated by a mixture of exchanges with an effective Regge trajectory of intercept alpha_i(0)=0.33 +- 0.04 stat +- 0.04 syst. The total cross section for the interaction of the photon with this mixture (gamma alpha_i -> X) can be described by an effective trajectory of intercept alpha_k(0)=0.99 +- 0.01 stat +- 0.05 syst. Predictions based on previous triple Regge analyses of pp-> pX data assuming vertex factorisation are broadly consistent with the gamma p data. The measured cross sections are compared with deep inelastic scattering leading proton data in the same region of z and pT_proton for photon virtuality Q^2 > 2.5 GeV^2. The ratio of the cross section for leading proton production to the total cross section is found to rise with Q^2.

A search for scalar and vector leptoquarks coupling to first generation fermions is performed in the H1 experiment at the ep collider HERA. The analysis uses e−p data collected in 1998 and 1999 at a centre-of-mass energy of 320 GeV, corresponding to an integrated luminosity of ∼15 pb−1. No evidence for the direct production of such particles is found in a data sample with a large transverse momentum final state electron or with large missing transverse momentum, and constraints on leptoquark models are established. For a Yukawa coupling of electromagnetic strength leptoquarks are excluded for masses up to ∼290 GeV. This analysis complements the leptoquark searches performed previously using data collected whilst HERA was operating with positrons instead of electrons.

A search for excited electron (e∗) production is described in which the electroweak decays e∗→eγ, e∗→eZ and e∗→νW are considered. The data used correspond to an integrated luminosity of 120 pb−1 taken in e±p collisions from 1994 to 2000 with the H1 detector at HERA at centre-of-mass energies of 300 and 318 GeV. No evidence for a signal is found. Mass dependent exclusion limits are derived for the ratio of the couplings to the compositeness scale, f/Λ. These limits extend the excluded region to higher masses than has been possible in previous direct searches for excited electrons.

The cross sections for the charged current processes ${e^{-}p}\rightarrow{\nu_e+hadrons}$ and, for the first time, ${e^{+}p}\rightarrow{\overline{\nu}_e+hadrons}$ are measured at HERA for transverse momenta larger than 25 GeV.

A measurement is presented of the cross section for D∗± meson production in diffractive deep-inelastic scattering for the first time at HERA. The cross section is given for the process ep→eXY, where the system X contains at least one D∗± meson and is separated by a large rapidity gap from a low mass proton remnant system Y. The cross section is presented in the diffractive deep-inelastic region defined by 2<Q2<100 GeV2, 0.05<y<0.7, xP<0.04, MY<1.6 GeV and |t|<1 GeV2. The D∗± mesons are restricted to the range pT,D∗>2 GeV and |ηD∗|<1.5. The cross section is found to be 246±54±56 pb and forms about 6% of the corresponding inclusive D∗± cross section. The cross section is presented as a function of various kinematic variables, including zPobs which is an estimate of the fraction of the momentum of the diffractive exchange carried by the parton entering the hard-subprocess. The data show a large component of the cross section at low zPobs where the contribution of the boson–gluon-fusion process is expected to dominate. The data are compared with several QCD-based calculations.

We present a search for excited neutrinos using e−p data taken by the H1 experiment at HERA at a center-of-mass energy of 318 GeV with an integrated luminosity of 15 pb−1. No evidence for excited neutrino production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f/Λ, independently of the relative couplings to the SU(2) and U(1) gauge bosons. These limits extend the excluded region to higher masses than has been possible in previous searches at other colliders.

The CMS pixel barrel system will consist of three layers built of about 800 modules. One module contains 66 560 readout channels and the full pixel barrel system about 48 million channels. It is mandatory to test each channel for functionality, noise level, trimming mechanism, and bump bonding quality. Different methods to determine the bump bonding yield with electrical measurements have been developed. Measurements of several operational parameters are also included in the qualification procedure. Among them are pixel noise, gains and pedestals. Test and qualification procedures of the pixel barrel modules are described and some results are presented.

A leading order determination of the gluon density in the proton has been performed in the fractional momentum range 1.9 · 10−3 < xg/p < 0.18 by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a kinematic region previously not accessible. The data show a considerable increase of the gluon density with decreasing fractional momenta of the gluons.

The front-end for the CMS pixel detector has been translated from the radiation hard DMILL process to a commercial 0.25μm technology. The smaller feature size of this technology permitted a reduction of the pixel size and other improvements. First results obtained with the translated chip are discussed.

Abstract The pixel detector of the CMS experiment will need to be replaced after a couple of years of LHC running because of radiation damage. On the other hand, plans for a step wise luminosity upgrade of the accelerator beyond the present design value around 2014 are being prepared. While the replacement pixel detector must be designed to handle increased particle rates, it should maintain or improve the tracking performance of the present system and must be compatible with existing services.

Photon-proton (γp) interactions with Q2 < 10−2 GeV2 and deep-inelastic scattering (γ∗p) interactions with photon virtualities Q2 > 5 GeV2 are studied at the high energy electron-proton collider HERA. The transverse energy flow and relative rates of large rapidity gap events are compared in the two event samples. The observed similarity between γp and γ∗p interactions can be understood in a picture where the photon develops as a hadronic object. The transverse energy density measured in the central region of the collision, at η∗ = 0 in the γ∗p centre of mass frame, is compared with data from hadron-hadron interactions as function of the CMS energy of the collision.

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.

For the barrel part of the CMS pixel tracker about 800 silicon pixel detector modules are required. The modules are bump bonded, assembled and tested at the Paul Scherrer Institute. This article describes the experience acquired during the assembly of the first ∼200 modules.

The Compact Muon Solenoid experiment at the Large Hadron Collider at CERN includes a silicon pixel detector as its innermost component. Its main task is the precise reconstruction of charged particles close to the primary interaction vertex. This paper gives an overview of the mechanical requirements and design choices for the barrel pixel detector. The distribution of material in the detector as well as its description in the Monte Carlo simulation are discussed in detail.

The inner tracking detectors at the LHC operate in a region of unprecedented particle rates. Thousands of hits must be detected, time-stamped and stored in every 25 ns bunch crossing interval. The silicon pixel detector for the CMS experiment has been designed to meet the requirements of position resolution, rate capability and radiation tolerance with a minimal amount of material. Its unique ability to provide three-dimensional high precision space points plays an important role in the tracking system of the CMS detector.

Pixel detectors are used in the innermost part of the multi purpose experiments at LHC and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of all detector components has thoroughly been tested up to the fluences expected at the LHC. In case of an LHC upgrade, the fluence will be much higher and it is not yet clear how long the present pixel modules will stay operative in such a harsh environment. The aim of this study was to establish such a limit as a benchmark for other possible detector concepts considered for the upgrade. As the sensors and the readout chip are the parts most sensitive to radiation damage, samples consisting of a small pixel sensor bump-bonded to a CMS-readout chip (PSI46V2.1) have been irradiated with positive 200 MeV pions at PSI up to 6E14 Neq and with 21 GeV protons at CERN up to 5E15 Neq. After irradiation the response of the system to beta particles from a Sr-90 source was measured to characterise the charge collection efficiency of the sensor. Radiation induced changes in the readout chip were also measured. The results show that the present pixel modules can be expected to be still operational after a fluence of 2.8E15 Neq. Samples irradiated up to 5E15 Neq still see the beta particles. However, further tests are needed to confirm whether a stable operation with high particle detection efficiency is possible after such a high fluence.

The fast and slow control of the central silicon tracker in H1 is performed by means of an ASIC decoder chip having four digital input lines. These control signals as well as the analog hit signals are transmitted to and from the detector through 34 m of optical fibers, which are composed of three connectable multifiber cables.

We present a search for excited electrons, neutrinos and quarks using the H1 detector at the ep collider HERA, based on data taken in 1994 with an integrated luminosity of 2.75 pb−1. Radiative decays of excited quarks and neutrinos have been investigated as well as decays of excited electrons into all possible electroweak gauge bosons. No evidence for new particle production is found and exclusion limits are derived.

A search for scalar top quarks in R-parity violating supersymmetry is performed in e+p collisions at HERA using the H1 detector. The data, taken at s=319GeV and 301 GeV, correspond to an integrated luminosity of 106pb−1. The resonant production of scalar top quarks t˜ in positron quark fusion via an R-parity violating Yukawa coupling λ′ is considered with the subsequent bosonic stop decay t˜→b˜W. The R-parity violating decay of the sbottom quark b˜→dν¯e and leptonic and hadronic W decays are considered. No evidence for stop production is found in the search for bosonic stop decays nor in a search for the direct R-parity violating decay t˜→eq. Mass dependent limits on λ′ are obtained in the framework of the minimal supersymmetric Standard Model. Stop quarks with masses up to 275GeV can be excluded at the 95% confidence level for a Yukawa coupling of electromagnetic strength.

A search for gravitinos produced in ep collisions is performed using the H1 detector at HERA. The data were taken at a centre-of-mass energy of 319 GeV and correspond to an integrated luminosity of 64.3 pb^{-1} for e^+p collisions and 13.5 pb^{-1} for e^-p collisions. If R-parity is not conserved, the t-channel exchange of a selectron can produce a neutralino, which, in models where the gravitino is the lightest supersymmetric particle, subsequently decays into a photon and a light gravitino. The resulting event signature, which involves an isolated photon, a jet and missing transverse energy, is analysed for the first time at HERA. No deviation from the Standard Model is found. Exclusion limits on the cross section and on R-parity-violating Yukawa couplings are derived in a Gauge Mediated Supersymmetry Breaking scenario. The results are independent of the squark sector. Neutralinos and supersymmetric partners of the left-handed electron with masses up to 112 GeV and 164 GeV, respectively, can be ruled out at the 95% confidence level for R-parity-violating couplings lambda' equal to 1.

Pixel detectors are used in the innermost part of multi purpose experiments at the Large Hadron Collider (LHC) and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of the detectors has thoroughly been tested up to the fluences expected at the LHC. In case of an LHC upgrade the fluence will be much higher and it is not yet clear up to which radii the present pixel technology can be used. In order to establish such a limit, pixel sensors of the size of one CMS pixel readout chip (PSI46V2.1) have been bump bonded and irradiated with positive pions up to 6E14 Neq/cm^2 at PSI and with protons up to 5E15 Neq/cm^2. The sensors were taken from production wafers of the CMS barrel pixel detector. They use n-type DOFZ material with a resistance of about 3.7kOhm cm and an n-side read out. As the performance of silicon sensors is limited by trapping, the response to a Sr-90 source was investigated. The highly energetic beta-particles represent a good approximation to minimum ionising particles. The bias dependence of the signal for a wide range of fluences will be presented.

Abstract Prototype double sided silicon strip detectors for the H1 vertex detector have been fabricated. The design uses integrated coupling capacitors on both sides and a second metal layer with readout lines on the n-side. Measurements of leakage currents, sheet resistances, metal line quality and contact reliability all show satisfactory results. A multi-guard structure improves the high-voltage and long-term stability of the detectors. The accumulation layer channel resistors on the n-side showed dramatic radiation effects after 60Co doses of 100 krad and an improved design with a metal gate electrode is demonstrated. Interstrip capacitances have been measured systematically on test structures with various geometries. The capacitance due to the second metal layer on the n-side has been measured for a 2 μm SiO2 and a 6 μm polyimide dielectric. Up to now, integrated coupling capacitors could not be fabricated with sufficiently low defect rates.

Vertexing is an important part of event reconstruction in CMS. Several non-linear reconstruction algorithms have been developed to improve the robustness of vertex fitting. An overview over the algorithms used in the CMS experiment is give, their properties are discussed and their performance on simulated data is shown.

A search for squarks ofR-parity violating supersymmetry is performed inep collisions at HERA using H1 1994e + data. Direct single production of squarks of each generation bye +-quark fusion via a Yukawa coupling λ′ is considered. All possibleR-parity violating decays and gauge decays of the squarks are taken into account. No significant deviation from the Standard Model predictions is found in the various multi-lepton and multi-jet final states studied and exclusion limits are derived. At 95% confidence level, the existence of first generation squarks is excluded for masses up to 240 GeV for coupling values λ′≳√4πα em. The limits obtained are shown to be only weakly dependent on the free parameters of the Minimal Supersymmetric Standard Model. Stop squarks are excluded for masses up to 138 GeV for coupling λ′×cosθ t toe +d pairs ≳0.1×√4πα em, whereθ t is the mass mixing angle. Light stop squarks are furthermore searched for through pair production inγ-gluon fusion processes. No signal is observed and exclusion limits are derived. Masses in the range 9 to 24.4 GeV are excluded at 95% confidence level for λ′×cosθ t>10−4.

A readout chip for the CMS pixel detector has been developed in the radiation hard DMILL process. The chips ability to operate under LHC conditions was tested in a high-rate pion beam with track densities up to 3×107cm−2s−1. The observed degradation of the detection efficiency with increasing particle flux is compared with the data-loss mechanisms inherent to the readout architecture. First detector modules with 16 chips on a low-mass high-density interconnect are evaluated. The next iteration of the readout chip is designed for a 0.25μm process with a radiation-tolerant layout.

The H1 experiment at the ep collider HERA has been equipped with a silicon strip detector, mainly for the purpose of heavy flavor physics. First results have recently become final. The vertexing techniques and strategies employed in H1 are reviewed.

MoTiC (Monolithic Timing Chip) is a prototype DMAPS Chip that builds on sensor technology developed in the ARCADIA project.The 50 by 50 µm 2 pixels contain a small charge collecting electrode with a very low capacitance surrounded by radiation-hard in-pixel electronics.The chip contains a matrix of 5120 pixels on an area of 3.2 by 4 mm 2 .Each pixel features a trimmable and maskable comparator with a sample and hold circuit for the analog pulse height.Groups of 4 pixels share a TDC situated also in the readout matrix.This work presents the chip design and preliminary results of the hit efficiencies and spatial resolution measured in a first test beam campaign with 4-5 GeV/c electrons conducted at DESY.

The proton structure function F2(x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ∼0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton–nucleon scattering experiments.

In den QUENCH-Versuchen wird der Wasserstoffquellterm bei der Einspeisung von Notkuhlwasser in einen trockenen, uberhitzten Reaktorkern eines Leichtwasserreaktors untersucht. Ferner wird in den Versuchen das Verhalten von uberhitzten Brennelementen unter verschiedenen Flutbedingungen untersucht, eine Datenbasis zur Modellentwicklung und eine Weiterentwicklung von Rechenprogrammen zu Schweren Storfallen (engl. SFD – Severe Fuel Damage) erstellt. Der Ausdampf-Versuch QUENCH-11 wurde am 8. Dezember 2005 durchgefuhrt. Es war das zweite Experiment im Rahmen des EU-geforderten LACOMERA-Programms. Es sollte einen Kuhlmittelpumpenausfall wahrend eines Kuhlmittelverluststorfalls (hier ein sog. Small Break LOCA) oder einer plotzlichen Stromabschaltung (eng. „station blackout“) mit einer spaten Druckentlastung des Primarsystems simulieren. Verbunden mit dem Unfallszenario ist das Ausdampfen eines teilgefullten Reaktorkerns bzw. des Versuchsbundels. Das Ziel war die Untersuchung des Bundelverhaltens wahrend des Ausdampfens und des nachfolgenden Abschreckens mit reduzierter Wassereinspeiserate. Es war das erste Experiment, in dem der gesamte Unfallablauf von der Ausdampfphase bis zur verzogerten Flutung des Bundels bei einer geringen Wasser-Einspeiserate untersucht werden sollte. Das Ausmas der Wechselwirkungen von Thermalhydraulik und Materialien war in dem Experiment ausgepragter als in fruheren QUENCH-Versuchen. Das Experiment wurde von INRNE Sofia (Bulgarische Akademie der Wissenschaften) vorgeschlagen und zusammen mit dem Forschungszentrum Karlsruhe definiert. Nach dem Experiment wurde entschieden, die QUENCH-11-Daten fur ein Rechenprogramm-Benchmark, bei dem die Rechenergebnisse mit den experimentellen Daten verglichen werden, im Rahmen des Europaischen Exzellenz-Netzwerks SARNET anzubieten, um die Zuverlassigkeit der Rechnungen fur die verschiedenen Phasen von Unfall bzw. Experiment zu uberprufen. Die eingesetzten SFD-Rechenprogramme waren ASTEC, ATHLET-CD, ICARE-CATHARE, MELCOR, RATEG/SVECHA, RELAP/SCDAPSIM, und SCDAP/RELAP5. Die Koordination fur den Vergleich ubernahm INRNE. Als Grundlage fur den Vergleich dienten die zeitlichen Verlaufe von Temperaturen, Wasserstofferzeugung und anderer wichtiger Daten. Auserdem wurden Axialprofile, in erster Linie die der Temperatur zum Zeitpunkt des Flutbeginns und des Endstadiums, d. h. bei der Testzeit von 7000 s, verglichen. Fur die meisten Rechenergebnisse kann ein gemeinsamer Trendverlauf angegeben werden. Grosere Unterschiede zeigen die Ergebnisse fur die Wasserstofferzeugung und die zugehorige Oxidschichtdicke. Der Grad der Ubereinstimmung zwischen Rechnung und Experiment wird von den Schwachstellen der Rechnung und des Experiments gleichermasen mitbestimmt. SFD-Rechenprogramme sind zur Analyse von typischen Kernreaktorunfallen entwickelt worden. Einzelne Besonderheiten der experimentellen Anordnung integraler Experimente (wie auch QUENCH-11) sind bedingt durch das Vorhandensein von Dampffuhrungsrohr (Shroud) und Elektrodenmaterial fur die elektrische Stabheizung nicht reaktortypisch und konnen daher nicht in der gewunschten Einzelheit im Rechenprogramm nachgebildet werden. Hinzu kommen Effekte durch den Anwender. Da jedoch die Bandbreite der wesentlichen Rechenergebnisse einschlieslich der Wasserstofferzeugung nicht extrem gros ist, kann das Ergebnis des SFD-Rechenprogramm-Benchmarks insgesamt als positiv bewertet werden. Ein Vergleich mit anderen Experimenten zeigt einen weiteren Bedarf an Verbesserungen besonders im Hinblick auf die Oxidation stark zerstorter Bundelstrukturen wahrend des Flutens. Zusatzlich erwies sich das Rechenprogramm-Benchmark fur einige Programmanwender als wertvoll, um sich mit den physikalischen Problematiken und der Anwendung von grosen SFD-Rechenprogrammen vertraut zu machen. Es dient dem Erfahrungsaustausch mit jungeren Wissenschaftlern und Ingenieuren und der Aufrechterhaltung des Standards der nuklearen Sicherheit.

The QUENCH experiments at the Karlsruhe Research Center are set up to investigate hydrogen source term generation that results from the water or steam injection into an uncovered core of a Light-Water Reactor (LWR), to examine the behavior of overheated fuel elements under different flooding conditions, and to create a database for model development and improvement of Severe Fuel Damage code packages. The test QUENCH-11 was conducted at the Karlsruhe Research Center on 8 December 2005 as the second of two experiments in the frame of the EC-supported LACOMERA program. The experiment is focused on studying the bundle behavior during boil-off and subsequent quenching at low water injection rate. The test was proposed by INRNE - Sofia, and defined together with the Karlsruhe Research Center. A SARNET benchmark problem is defined as a comparison between QUENCH-11 experimental data and analytical results received from the different computer codes such as ASTEC, ICARE-CATHARE, MELCOR, RELAP5/SCDAP, RELAP/SCDAPSIM, RATEG/SVECHA, and ATHLET-CD. In total ten participants from seven countries participated in this exercise.