The exhumation of the Indo-Burman Ranges, Myanmar

The Indo-Burman Ranges (IBR) are a mountain range comprised of Mesozoic-Cenozoic rocks which run the length of Western Myanmar, extending into India and Bangladesh; to the west lies the Indian Ocean, and to the east lies the Central Myanmar Basin (CMB) along which the Irrawaddy River flows. The IBR are considered to be an accretionary prism, developed at the juncture of the Indian and Sunda plates, and a number of hypotheses have been proposed for their evolution. However, in order for these hypotheses to be evaluated, the timing of IBR evolution needs to be determined. We undertook a two-pronged approach to determining the timing of uplift of the IBR. (1) We present the first low-temperature thermochronological age elevation profiles of the IBR using ZFT, AFT and ZHe techniques. Our data show: a major period of exhumation occurred around the time of the Oligo-Miocene boundary; we tentatively suggest, subject to further verification, an additional period of exhumation at or before the late Eocene. (2) We carried out a detailed multi-technique provenance study of the sedimentary rocks of the IBR and Arakan Coastal region to their west, and compared data to coeval rocks of the CMB. We determined that during Eocene times, rocks of the CMB and IBR were derived from similar local provenance, that of the Myanmar arc to the east. Therefore at this time there was an open connection from arc to ocean. By contrast, by Miocene times, provenance diverged. Rocks of the CMB were deposited by a through-flowing Irrawaddy River, with detritus derived from its upland source region of the Mogok Metamorphic Belt and Cretaceous-Paleogene granites to the north. Such a provenance is not recorded in coeval rocks of the IBR, indicating that the IBR had uplifted by this time, providing a barrier to transport of material to the west. To the previously published list of viable proposals to explain the exhumation of the range, we add a new suggestion: the period of exhumation around the time of the Oligo-Miocene boundary could have been governed by a change to wedge dynamics instigated by a major increase in the thickness of the incoming Bengal Fan sediment pile

Negative hydrogen ion sources for particle accelerators: Sustainability issues and recent improvements in long-term operations

High brightness, negative hydrogen ion sources are used extensively in scientific facilities operating worldwide. Negative hydrogen beams have become the preferred means of filling circular accelerators and storage rings as well as enabling efficient extraction from cyclotrons. Several well-known facilities now have considerable experience with operating a variety of sources such as RF-, filament-, magnetron- and Penning-type H$^{-}$ ion sources. These facilities include the US Spallation Neutron Source (SNS), Japan Proton Accelerator Research Complex (J-PARC), Rutherford Appleton Laboratory (RAL-ISIS), Los Alamos Neutron Science Center (LANSCE), Fermi National Accelerator Laboratory (FNAL), Brookhaven National Laboratory (BNL), numerous installations of D-Pace (licenced by TRIUMF) ion sources used mainly on cyclotrons and, most recently, the CERN-LINAC-1 injector. This report first summarizes the current performance of these ion sources in routine, daily operations with attention toward source service-periods and availability metrics. Sustainability issues encountered at each facility are also reported and categorized to identify areas of common concern and key issues. Recent ion source improvements to address these issues are also discussed as well as plans for meeting future facility upgrade requirements

The CMS Barrel Calorimeter Response to Particle Beams from 2 to 350 GeV/c

The response of the CMS barrel calorimeter (electromagnetic plus hadronic) to hadrons, electrons and muons over a wide momentum range from 2 to 350 GeV/c has been measured. To our knowledge, this is the widest range of momenta in which any calorimeter system has been studied. These tests, carried out at the H2 beam-line at CERN, provide a wealth of information, especially at low energies. The analysis of the differences in calorimeter response to charged pions, kaons, protons and antiprotons and a detailed discussion of the underlying phenomena are presented. We also show techniques that apply corrections to the signals from the considerably different electromagnetic (EB) and hadronic (HB) barrel calorimeters in reconstructing the energies of hadrons. Above 5 GeV/c, these corrections improve the energy resolution of the combined system where the stochastic term equals 84.7$\pm$1.6$\%$ and the constant term is 7.4$\pm$0.8$\%$. The corrected mean response remains constant within 1.3$\%$ rms

Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at (s)\sqrt(s) = 0.9 and 2.36 TeV

Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at sqrt(s) = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between -2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN(charged)/d(eta) for |eta| < 0.5, are 3.48 +/- 0.02 (stat.) +/- 0.13 (syst.) and 4.47 +/- 0.04 (stat.) +/- 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in p-pbar and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date