L. Uvarov

We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.

We observe a signal for the doubly charmed baryon Ξcc+ in the decay mode Ξcc+→pD+K− to complement the previous reported decay Ξcc+→Λc+K−π+ in data from SELEX, the charm hadroproduction experiment at Fermilab. In this new decay mode we observe an excess of 5.62 events over a combinatoric background estimated by event mixing to be 1.38±0.13 events. The mixed background has Gaussian statistics, giving a signal significance of 4.8σ. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4×10−4. The observed mass of this state is 3518±3MeV/c2, consistent with the published result. Averaging the two results gives a mass of 3518.7±1.7MeV/c2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio for these two modes is 0.36±0.21.

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

We present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for Λ̄c− compared to Λc+ as a function of xF, and on pt2 distributions for Λc+. These data were measured in the same apparatus using incident π−, Σ− beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of xF. In the forward hemisphere with xF⩾0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Λc formation, as suggested by the leading quark picture.

We report new precision measurements of the lifetimes of the ${\ensuremath{\Lambda}}_{c}^{+}$ and ${D}^{0}$ from SELEX, the charm hadroproduction experiment at Fermilab. Based upon 1630 ${\ensuremath{\Lambda}}_{c}^{+}$ and 10 210 ${D}^{0}$ decays we observe lifetimes of $\ensuremath{\tau}[{\ensuremath{\Lambda}}_{c}^{+}]\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}198.1\ifmmode\pm\else\textpm\fi{}7.0\ifmmode\pm\else\textpm\fi{}5.6\mathrm{fs}$ and $\ensuremath{\tau}[{D}^{0}]\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}407.9\ifmmode\pm\else\textpm\fi{}6.0\ifmmode\pm\else\textpm\fi{}4.3\mathrm{fs}$.

Differential cross sections for the process pi +d to pp at seven energies in the region Tpi =280-450 MeV and in the angular range theta * approximately=4-90 degrees have been measured on the LNPI synchrocyclotron. The results include 94 new data points. The measurements have been carried out using a ten-channel hodoscope set-up. Statistical errors are between 2.5% and 7.8% depending on the scattering angle and Tpi . The data obtained indicate that there is an essential contribution from the partial wave with orbital angular momentum l=3 over the whole energy range considered. The authors also observe a noticeable contribution from the l=4 partial wave to the differential cross sections of the pi +d to pp reaction from Tpi >or=357 MeV. The total cross sections for the process pi +d to pp are also presented.

We report a precise measurement of the D±s meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Σ−, π− and p beams. The measurement has been done using 918 reconstructed D±s. The lifetime of the D±s is measured to be 472.5±17.2±6.6 fs, using K∗(892)0K± and φπ± decay modes. The lifetime ratio of Ds± to D0 is 1.145±0.049.

Using data taken by SELEX during the 1996–1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with Σ −, p, π −, and π + beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as A α , we determine α for D +, D 0, D + , D +(2010), Λ + , and their respective anti-particles, as a function of their transverse momentum p t and scaled longitudinal momentum x F . Within our statistics there is no dependence of α on x F for any charm species for the interval 0.1<x F <1.0. The average value of α for charm production by pion beams is α meson=0.850±0.028. This is somewhat larger than the corresponding average α baryon=0.755±0.016 for charm production by baryon beams (Σ −, p).

We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/c Σ−, π− and 540GeV/c p beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.

We present the design of a fast three-dimensional track-finding processor for the Level-1 trigger of the CMS Endcap Muon System. Each track is assembled from track segments identified in the Endcap Muon chambers. The processor measures the transverse momentum of the best muon candidates from the sagitta induced by the magnetic bending. The trigger algorithms are programmable since the processor is based on FPGA and RAM logic, allowing the experiment to adapt to different background conditions and colliding rates.

In the Compact Muon Solenoid (CMS) experiment, muon detection in the forward direction is accomplished by cathode strip chambers (CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using 36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge (MTCC) exercise conducted by the CMS experiment in 2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<0.01m2), results presented in this paper were obtained by many installed CSCs operating in situ over an area of ≈23m2 as a part of the CMS experiment. The efficiency of finding two-dimensional trigger primitives within six-layer chambers was found to be 99.93±0.03%. These segments, found by the CSC electronics within 800 ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System.

The readout electronics designed for the DO Muon Upgrade are described. These electronics serve three detector subsystems and one trigger system. The front-ends and readout hardware are synchronized by means of timing signals broadcast from the DO Trigger Framework. The front-end electronics have continuously running digitizers and two levels of buffering resulting in nearly deadtimeless operation. The raw data is corrected and formatted by 16-bit fixed point DSP processors. These processors also perform control of the data buffering. The data transfer from the front-end electronics located on the detector platform is performed by serial links running at 160 Mbit/s. The design and test results of the subsystem readout electronics and system interface are discussed.

The production, installation, and testing of 468 cathode strip chambers for the endcap muon system of the CMS experiment played a critical role in the preparation of the endcap muon system for the final commissioning. Common testing procedures and sets of standard equipment were used at 5 international assembly centers. The chambers were then thoroughly retested after shipment to CERN. Final testing was performed after chamber installation on the steel disks in the CMS detector assembly building. The structure of the detector quality control procedure is presented along with the results of chamber performance validation tests.

This note describes the installation of the CSC Track Finder in the CMS Underground Service Cavern. Specific details of the location and type of electronics boards, fiber and cable connections pertaining to the crate are given.

The conceptual design for a Level-1 muon track-finder trigger for the CMS endcap muon system is proposed that can accommodate the increased particle occupancy and system constraints of the proposed SLHC accelerator upgrade and the CMS detector upgrades. A brief review of the architecture of the current track-finder for LHC trigger operation is given, with potential bottlenecks indicated for SLHC operation. The upgraded track-finding processors described here would receive as many as two track segments detected from every cathode strip chamber comprising the endcap muon system, up to a total of 18 per 60° azimuthal sector. This would dramatically improve the efficiency of the track reconstruction in a high occupancy environment over the current design. However, such an improvement would require significantly higher bandwidth and logic resources. We propose to use the fastest available serial links, running asynchronously to the machine clock to use their full bandwidth. The work of creating a firmware model for the upgraded Sector Processor is in progress; details of its implementation will be discussed. Another enhancement critical for the overall Level-1 trigger capability for physics studies in phase 2 of the SLHC is to include the inner silicon tracking systems into the design of the Level-1 trigger. I. CMS ENDCAP MUON LEVEL-1 TRIGGER SYSTEM OVERVIEW The CMS Endcap Muon system consists of 540 six-plane cathode strip chambers. Strips, milled on the cathode panels, run radially in the endcap geometry and thus provide a precise measurement of the φ-coordinate. Wires are stretched across strips and define the radial coordinate of muon hits. A. Generation of Trigger Primitives Electronic components responsible for the generation of trigger primitives include:  Cathode Front End Board (CFEB), 5 per chamber  Anode Local Charged Track board (ALCT), 1 per chamber  Trigger Mother Board (TMB), 1 per chamber The CMS Endcap Muon system is comprised of two endcaps. Each endcap consists of 4 layers of Cathode Strip 1 468 chambers installed and operational and 72 additional chambers (ME4/2) to be fabricated and installed. Chambers (CSCs); these layers are commonly called “stations”. Station ME1 is the closest to the Interaction Point (IP), station ME4 is the farthest. For the purposes of Trigger system, each endcap is subdivided into six 60o sectors. Each sector is served by one Sector Processor (SP) board; there are 12 SPs in the Endcap Muon Trigger system. Each SP is implemented as a 9U VME board; all SPs are housed in one VME crate that is located in the CMS Underground Support Cavern (USC55). The TMB associated with each chamber can provide up to two trigger primitives on any bunch crossing. Each trigger primitive contains the following information:  Cathode hit coordinate (half-strip number)  Cathode pattern type (measure of the track bend angle)  Anode hit coordinate (wiregroup number)  Anode pattern type (collision or halo track)  Trigger primitive quality The trigger primitives generated by TMBs are delivered to Muon Port Cards (MPC), also located in the Peripheral Crates. There is one MPC per station (9 chambers), except station 1 that has 2 MPCs because there are 18 chambers in it. Each MPC receives up to 18 trigger primitives per bunchcrossing (BX). The MPC selects the best three trigger primitives out of 18, and sends them via 1.6 Gbps optical links to the Sector Processor. B. Track reconstruction in Sector Processor The Sector Processor (SP) receives trigger primitives from MPCs associated with all stations in a specific sector, for a total of up to 15 primitives per BX. In addition to that, the Barrel Muon system (Drift Tube Chambers, or DT) delivers up to two trigger primitives from the region where it overlaps with the Endcap Muon system. If one or two more DT trigger primitives are available at the same BX, they can be delivered with a delay of one clock cycle. Track reconstruction involves the following hardware modules: 1) Conversion of raw trigger primitives into geometrical parameters. In the current design, the conversion of raw trigger primitives into φ and η (pseudorapidity) is performed using

We report on the design and test results of a prototype processor for the CMS Level-1 trigger that performs 3-D track reconstruction and measurement from data recorded by the cathode strip chambers of the endcap muon system. The tracking algorithms are written in C++ using a class library we developed that facilitates automatic conversion to Verilog. The code is synthesized into firmware for field-programmable gate-arrays from the Xilinx Virtex-II series. A second-generation prototype has been developed and is currently under test. It performs regional track-finding in a 60 degree azimuthal sector and accepts 3 GB/s of input data synchronously with the 40 MHz beam crossing frequency. The latency of the track-finding algorithms is expected to be 250 ns, including geometrical alignment correction of incoming track segments and a final momentum assignment based on the muon trajectory in the non-uniform magnetic field in the CMS endcaps.