Development and property study of the extremely thin 12 \texorpdfstring{μm\mu m} C-type straw tubes with 5-mm diameter for a Straw Tracker System of COMET

The COMET experiment focuses on searching for the direct conversion of a muon into an electron with aluminum nuclei without emitting a neutrino (so-called $\mu\rightarrow e$ conversion). This conversion violates charged lepton flavor conservation law, a fundamental principle in the Standard Model. The COMET experiment requirement is to achieve the muon-to-electron conversation sensitivity on a level of $10^{-17}$. The Straw Tracker System (STS) based on straw tubes could provide the necessary spatial resolution of 150 $\mu$m and the electron momentum resolution better than 200 keV/c. The COMET experiment will be separated into two phases. Phase-I will operate with the 3.2 kW 8-GeV-proton beam, and Phase-II will operate with beam intensity increased to 56 kW. STS must operate in a vacuum with 1 bar internal pressure applied to straws. The initial design of 10-mm-diameter straws developed for phase-I will not be as efficient with the 20 times increased beam intensity of Phase II, but the new STS design based on 5-mm-diameter 12-$\mu$m thick straws could fully satisfy the required efficiency. The mechanical properties of these straws, such as sagging, elongation, dependence of the diameter on over-pressure, etc, are discussed in this article

Design and construction of new central and forward muon counters for CDF II

New scintillation counters have been designed and constructed for the CDF upgrade in order to complete the muon coverage of the central CDF detector, and to extend this coverage to larger pseudorapidity. A novel light collection technique using wavelength shifting fibers, together with high quality polystyrene-based scintillator resulted in compact counters with good and stable light collection efficiency over lengths extending up to 320 cm. Their design and construction is described and results of their initial performance are reported.Comment: 20 pages, 15 figure

CDF central preshower and crack detector upgrade

The CDF Central Preshower and Crack Detector Upgrade consist of scintillator tiles with embedded wavelength-shifting fibers, clear-fiber optical cables, and multi-anode photomultiplier readout. A description of the detector design, test results from R&D studies, and construction phase are reported. The upgrade was installed late in 2004, and a large amount of proton-antiproton collider data has been collected since then. Detector studies using those data are also discussed

Development of a New Clusterization Method for the GEM-TPC Detector

The Facility for Antiproton and Ion Research FAIR, in Darmstadt Germany, will be one of the largest accelerator laboratories worldwide. The Superconducting FRagment Separator (Super-FRS)* is one of its main components. The Super-FRS can produce, separate and deliver high-energy radioactive beams with intensities up to 1e11 ions/s, covering projectiles from protons up to uranium and it can be used as an independent experimental device. The Gas Electron Multiplier-based Time Projection Chambers (GEM-TPC) in twin configuration is a newly developed beam tracking detector capable of providing spatial resolution of less than 1 mm with a tracking efficiency close to 100% at 1 MHz counting rate. The GEM-TPC (HGB4) was tested at the FRagment Separator (FRS), with 238U beam at 850 MeV/u. A new clusterization method was developed, for the first time and used for an analysis. This method allowed to access to waveforms of each strip signal within a single trigger in an event-by-event basis. The procedures involved in this method will be shown in details.Peer reviewe

Measurement of the Lifetime Difference Between B_s Mass Eigenstates

We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_s system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203 +/- 15 B_s decays, we obtain tau_L = (1.05 +{0.16}/-{0.13} +/- 0.02) ps and tau_H = (2.07 +{0.58}/-{0.46} +/- 0.03) ps. Expressed in terms of the difference DeltaGamma_s and average Gamma_s, of the decay rates of the two eigenstates, the results are DeltaGamma_s/Gamma_s = (65 +{25}/-{33} +/- 1)%, and DeltaGamma_s = (0.47 +{0.19}/-{0.24} +/- 0.01) inverse ps.Comment: 8 pages, 3 figures, 2 tables; as published in Physical Review Letters on 16 March 2005; revisions are for length and typesetting only, no changes in results or conclusion