Recent results of the searches for Supersymmetry in final states with one or two leptons at CMS are presented. Many Supersymmetry scenarios, including the Constrained Minimal Supersymmetric extension of the Standard Model (CMSSM), predict a substantial amount of events containing leptons, while the largest fraction of Standard Model background events -which are QCD interactions -gets strongly reduced by requiring isolated leptons. The analyzed data was taken in 2011 and corresponds to an integrated luminosity of approximately L = 1 fb −1 . The center-of-mass energy of the pp collisions was √ s = 7 TeV.

SummaryThis document provides a detailed study of materials used to shield against the hadronic particles from cosmic ray showers at Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during transport for the MAJORANA collaboration. The materials suitable for cosmic-ray shield design are materials such as lead and iron that will stop the primary protons, and materials like polyethylene, borated polyethylene, concrete and water that will stop the induced neutrons. The interaction of the different cosmic-ray components at ground level (protons, neutrons, muons) with their wide energy range (from kilo-electron volts to giga-electron volts) is a complex calculation. Monte Carlo calculations have proven to be a suitable tool for the simulation of nucleon transport, including hadron interactions and radioactive isotope production. The Monte Carlo simulation tool Geant4 was used for this study.This document is structured to explicitly present the data and its analysis for the six different materials considered. Each material is analyzed according to it geometry, considering ten different thicknesses of each material plus no material. The intent of this document is to provide practical guidance in the choice of shielding material for the energy range of interest (20 MeV to 10 GeV) and its particular configuration. The hydrogenous materials modeled for this study were polyethylene (PE), borated polyethylene (BPE), and water. The effectiveness of each of these materials in shielding cosmic neutrons, protons and muons was similarly poor. None of these is therefore recommended as a material to consider in shielding the detector materials in transport from cosmic rays.The result of this study is the assertion that activation at Earth's surface is a result of the neutronic and protonic components of the cosmic-ray shower. The best material to shield against these cosmic-ray components is iron, which has the best combination of primary shielding and minimal secondary neutron production.

SummaryThis document describes the construction of and results from the Majorana Cosmic Ray (MaCoR) software tool, developed to model the hadronic interactions of cosmic rays with different geometries and materials. The ubiquity of cosmic radiation in the environment results in the activation of stable isotopes, referred to as cosmogenic activation. The objective is to use this application in conjunction with a model of the MAJORANA DEMONSTRATOR components, from extraction to deployment, to evaluate cosmogenic activation of such components before deployment. The cosmic ray showers include several types of particles with a wide range of energy (MeV to GeV). It is infeasible to compute an exact result with a deterministic algorithm for this problem; Monte Carlo simulations are a more suitable approach to model cosmic ray hadronic interactions. The tool is based on the Geant4 toolkit. This toolkit was chosen for its end to end nature and ability to simulate energies up to GeV. Another aspect of Geant4 that was used in this work is its flexibility and ability to accommodate external source particles libraries. Other tools such as MCNP or FLUKA lack part of these features. In order to validate the results generated by the application, a test comparing experimental muon flux measurements and those predicted by the application is presented. The experimental and simulated results have a deviation of 3%.

This report presents the experimental results of PNNL's MAJORANA DEMONSTRATOR prototype cooling system. The MAJORANA DEMONSTRATOR high-purity germanium (HPGe) detector modules should operate as close to liquid nitrogen temperature as possible to provide adequate cooling for a full range of HPGe impurity concentrations. In addition, exceptional temperature stability (<1 K) is needed to reduce electronic gain shifts due to changes in the front end FET operating temperature. One approach is to use the two-phase liquid-gas equilibrium to ensure constant temperature. The MAJORANA DEMONSTRATOR cooling system is required to transport the heat ~1 meter from the detectors located inside a lead and copper shield to a liquid nitrogen Dewar outside the shield. Two-phase cooling results in near zero temperature difference over this distance in contrast to the several degrees Kelvin that would result from a system that conducts the heat through a massive copper cold finger. Furthermore, the tube required for a two-phase system can more readily be produced by electroforming (required for radiopurity) than a massive cold finger. A nitrogen thermosyphon can be designed so the vaporization/condensation process transfers heat through the shield while maintaining a stable operating temperature. A prototype of such a system has been built and tested at PNNL. This document presents the experimental results of the prototype and evaluates the heat transfer performance of the system.

SummaryThis document presents results of an investigation of the material and geometry choice for the transport cosmogenic shield of enriched germanium, the active detector material used in the MAJORANA DEMONSTRATOR neutrinoless double-beta decay search. The objective of this work is to select the optimal material and geometry to minimize cosmogenic production of radioactive isotopes in the germanium material during transport. The design of such a shield is based on the calculation of the cosmogenic production rate of isotopes that are known to cause interfering backgrounds in enriched germanium neutrinoless double-beta decay searches. As part of this study, we will examine the reliability of estimates of cosmogenic activation from this study under different shielding scenarios.This study utilizes Monte Carlo techniques to simulate the transport and attenuation of the incident cosmic ray particles in the shielding material and the nuclear reactions in the germanium. This method of calculating production rates relies completely on the accuracy of the simulation model and library data. The calculated production rate of an isotope is the product of the energy-dependent cross section of the reaction of interest and the incoming cosmic ray produced flux of particles, integrated over the relevant energy range. The production of 68 Ge from the various germanium isotopes have Q values starting at approximately 20 MeV, so the energy range of interest in this study is above 20 MeV. Based on the transport shield design used by GERDA and the MAJORANA DEMONSTRATOR, we present one modification to the shield that will further reduce the production rate of undesired isotopes 68 Ge and 60 Co and still comply with requirements of official transportation standards. The conclusion, based on Monte Carlo models, is that increasing the amount of iron to the container's maximum allowable weight results in a shield that would be an order of magnitude more efficient in the attenuation of the production of isotopes of interest for neutrinoless double-beta decay searches than the current GERDA transport shield design.