This paper describes methods for evaluating and characterising the integrity of machined surfaces in a powder nickel alloy that is being used for disc applications in aircraft engines. It initially reviews techniques for inspecting the effects of process parameters on surface integrity for hole making and finish turning and then presents the findings of work that has been conducted to understand the influence of machining anomalies on fatigue life. The techniques considered for characterising surface integrity include surface inspection, surface roughness measurement, metallographic assessment of etched surfaces using light microscopy and micro-hardness measurement. More novel techniques are then discussed, exploiting advanced electron microscopy, nano-indentation and x-ray diffraction methods. These are capable of understanding the effects of machining processes on microstructure and quantifying the depth to which machining processes can change the material microstructure.

Measurements of the efficiency, pulse shape, and energy and time resolution of liquid argon (LAr) detectors are presented. Liquefied noble gas-based (LNbG) detectors have been developed for the detection of dark matter and neutrinoless double-beta decay. However, the same qualities that make LNbG detectors ideal for these applications, namely their size, cost, efficiency, pulse shape discrimination and resolution, make them promising for portal screening and the detection of Special Nuclear Materials (SNM). Two 18-liter prototype detectors were designed, fabricated, and tested, one with pure LAr and the other doped with liquid Xe (LArXe). The LArXe detector presented the better time and energy resolution of 3.3 ns and 20% at 662 KeV, respectively. The total efficiency of the detector was measured to be 35% with 4.5% of the total photons detected in the photopeak.

The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP–nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large (>1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 m to be achieved in approximately 2 days and sustained for the duration of the testing period.

The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles (WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross-section per nucleon of 2 x 10(-46) cm(2), equivalent to similar to 1 event 100 kg month in the inner 100-kg fiducial volume (FV) of the 370-kg detector. The overall background goals are set to have <1 background events characterized as possible WIMPs in the FV in 300 days of running.This paper describes the design and construction of the LUX detector. (C) 2012 Elsevier B.V. All rights reserved.

Liquefied noble gas (LNG) detectors have already been successfully employed in areas of fundamental particle physics research due to features such as their high energy resolution, fast response times, excellent discrimination between neutron and gamma-ray interactions, and relatively low cost. Such detectors are also attractive for nonintrusive inspection for the presence of special nuclear material (SNM) in large-scale objects such as cargo containers and trucks. An effective method of interrogation involves pulsing the object being interrogated with neutrons, which induces fission in the SNM. The fission reaction promptly releases gamma rays and neutrons. This reaction can be distinguished from background through the coincidence measurement of these particles striking multiple detectors. Rapiscan Laboratories, Yale University Physics Department, and Adelphi Technology have constructed two 18-L liquid argon prototype detectors to investigate the suitability of LNG detectors in performing this form of interrogation. The pulse shape, energy resolution, time resolution, detector efficiency, and the effects of doping with xenon were measured.

White layers and extensive material drag introduced during rough machining are regarded as detrimental to surface integrity. As such a sensible method for determining the amount of material to be removed in a roughing process would be to understand the relationship and interaction between roughing (i.e. drilling) and finishing (i.e. plunge milling) operations. Within this work non-standard cutting parameters were employed during the roughing process to generate a white layer and material drag up to a depth of 20μm. Various plunge milling cutting strategies followed, with radius removal ranging from 25μm to 250μm in order to identify the amount of material removal necessary to eliminate the anomalies previously generated from mistreated surface history. The results show that finishing with a depth of cut between 50μm and 125μm removes all anomalies from the roughing process, leaving behind a negligible amount of material drag (3–4μm). X-ray diffraction demonstrates significant tensile residual stresses (1000–2000MPa) were generated in the axial and hoop direction by abusive hole drilling while subsequent plunge milling operation leaves compressive surface stresses in the region of −500MPa in both the axial and hoop directions; in both cases the depth of the surface stresses extended to around 125μm from the drilled surface. It was also found that a depth of cut of 25μm was not sufficient to recover the abused surface; this was due to intense material drag accompanied by surface cracking (i.e. 2μm depth). The research shows that understanding the interaction between successive cutting operations can provide a suitable machining route to fulfil the industrial quality requirements in terms of the machined surface mechanical/metallurgical properties.

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously.

We report results of a search for light (≲10  GeV) particle dark matter with the XENON10 detector. The event trigger was sensitive to a single electron, with the analysis threshold of 5 electrons corresponding to 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections σ(n)>7×10(-42)  cm(2), for a dark matter particle mass m(χ)=7  GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal.

We show that the energy threshold for nuclear recoils in the XENON10 dark matter search data can be lowered to ~1 keV, by using only the ionization signal. In other words, we make no requirement that a valid event contain a primary scintillation signal. We therefore relinquish incident particle type discrimination, which is based on the ratio of ionization to scintillation in liquid xenon. This method compromises the detector's ability to precisely determine the z coordinate of a particle interaction. However, we show for the first time that it is possible to discriminate bulk events from surface events based solely on the ionization signal.

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and ionization signal (S2), which are both functions of the deposited recoil energy and the incident particle type. We present a new precision measurement of the relative scintillation yield View the MathML source and the absolute ionization yield View the MathML source, for nuclear recoils in xenon. A dark matter particle is expected to deposit energy by scattering from a xenon nucleus. Knowledge of View the MathML source is therefore crucial for establishing the energy threshold of the experiment; this in turn determines the sensitivity to particle dark matter. Our View the MathML source measurement is in agreement with recent theoretical predictions above 15 keV nuclear recoil energy, and the energy threshold of the measurement is View the MathML source. A knowledge of the ionization yield View the MathML source is necessary to establish the trigger threshold of the experiment. The ionization yield View the MathML source is measured in two ways, both in agreement with previous measurements and with a factor of 10 lower energy threshold. The scintillation and ionization yield of liquid xenon for nuclear recoils P. Sorensen∗,a, A. Manzuri, C.E. Dahlf, J. Anglel,j, E. Aprilec, F. Arneodod, L. Baudisl, A. Bernsteine, A. Bolozdynyab, L.C.C. Coelhok, L. DeViveirosa, A.D. Ferellal,d, L.M.P. Fernandesk, S. Fioruccia, R.J. Gaitskella, K.L. Gibonic, R. Gomezg, R. Hastyi, L. Kastensi, J. Kwongf, J.A.M. Lopesk, N. Maddene, A. Manalaysayl,j, D.N. McKinseyi, M.E. Monzanic, K. Nii, U. Oberlackg, J. Orboeckh, G. Plantei, R. Santorellic, J.M.F. dos Santosk, P. Shaging, T. Shuttb, S. Schulteh, C. Winante, M. Yamashitac aDepartment of Physics, Brown University, Providence, RI 02912, USA bDepartment of Physics, Case Western Reserve University, Cleveland, OH 44106, USA cDepartment of Physics, Columbia University, New York, NY 10027, USA dGran Sasso National Laboratory, Assergi, L’Aquila, 67010, Italy eLawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA fDepartment of Physics, Princeton University, Princeton, NJ 08540, USA gDepartment of Physics, Rice University, Houston, TX 77251, USA hDepartment of Physics, RWTH Aachen University, Aachen, 52074, Germany iDepartment of Physics, Yale University, New Haven, CT 06511, USA jDepartment of Physics, University of Florida, Gainesville, FL 32611, USA kDepartment of Physics, University of Coimbra, R. Larga, 3004-516, Coimbra, Portugal lPhysics Institute, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland

XENON10 is an experiment to directly detect weakly interacting massive particles (WIMPs), which may comprise the bulk of the nonbaryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with 129Xe and 131Xe from 58.6 live days of operation at the Laboratori Nazionali del Gran Sasso. Based on the nonobservation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of ∼10 GeV/c2-2 TeV/c2 as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

The energy and electric field dependence of pulse shape discrimination in liquid xenon have been measured in a 10 g two-phase xenon time projection chamber. We have demonstrated the use of the pulse shape and charge-to-light ratio simultaneously to obtain a leakage below that achievable by either discriminant alone. A Monte Carlo is used to show that the dominant fluctuation in the pulse shape quantity is statistical in nature, and project the performance of these techniques in larger detectors. Although the performance is generally weak at low energies relevant to elastic WIMP recoil searches, the pulse shape can be used in probing for higher energy inelastic WIMP recoils.

It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to Enr=75 keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses mχ≳150 GeV are disfavored. Constraints on inelastic dark matter from XENON10 J. Angle, 2 E. Aprile, F. Arneodo, L. Baudis, A. Bernstein, A. Bolozdynya, L.C.C. Coelho, C.E. Dahl, L. DeViveiros, A.D. Ferella, 4 L.M.P. Fernandes, S. Fiorucci, R.J. Gaitskell, K.L. Giboni, R. Gomez, R. Hasty, L. Kastens, J. Kwong, J.A.M. Lopes, N. Madden, A. Manalaysay, 2 A. Manzur, D.N. McKinsey, M.E. Monzani, K. Ni, U. Oberlack, J. Orboeck, G. Plante, R. Santorelli, J.M.F. dos Santos, P. Shagin, T. Shutt, P. Sorensen, ∗ S. Schulte, C. Winant, and M. Yamashita (XENON10 Collaboration) Department of Physics, University of Florida, Gainesville, FL 32611, USA Physics Institute, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland Department of Physics, Columbia University, New York, NY 10027, USA Gran Sasso National Laboratory, Assergi, L’Aquila, 67010, Italy Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA Department of Physics, University of Coimbra, R. Larga, 3004-516, Coimbra, Portugal Department of Physics, Princeton University, Princeton, NJ 08540, USA Department of Physics, Brown University, Providence, RI 02912, USA Department of Physics and Astronomy, Rice University, Houston, TX 77251, USA Department of Physics, Yale University, New Haven, CT 06511, USA Department of Physics, RWTH Aachen University, Aachen, 52074, Germany (Dated: January 27, 2010) It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to Enr = 75 keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses mχ & 150 GeV are disfavored. PACS numbers: 95.35.+d, 14.80.Ly, 29.40.Gx, 95.55.Vj

This paper describes results on R&D of an economical and efficient cryogenic system for the LUX detector. LUX is a new WIMP dark matter search experiment to be carried out at the Homestake (South Dakota) gold mine, and is based on 300 kg of liquid xenon (LXe) operated at a temperature of 175 K. The cooling system consists of a cold head attached to a thermal screen surrounding the cold vessel and three nitrogen-filled thermosyphons designed to transport heat loads to a free-boiling liquid nitrogen bath. The most powerful thermosyphon mounted directly onto the cold head has demonstrated > 1 kW cooling power and has been used for the initial cooling of the detector and xenon condensation. The second thermosyphon with ~ 0.2 kW cooling power is mounted to the cold head through a thermal impedance designed for stable operation of the detector when the condensation is completed. The third thermosyphon similar to the second one is connected to the bottom of the thermal screen to control the temperature gradient along the detector. Results of initial tests are presented.

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and ionization signal (S2), which are both functions of the deposited recoil energy and the incident particle type. We present a new precision measurement of the relative scintillation yield Leff and the absolute ionization yield Qy, for nuclear recoils in xenon. A dark matter particle is expected to deposit energy by scattering from a xenon nucleus. Knowledge of Leff is therefore crucial for establishing the energy threshold of the experiment; this in turn determines the sensitivity to particle dark matter. Our Leff measurement is in agreement with recent theoretical predictions above 15keV nuclear recoil energy, and the energy threshold of the measurement is ∼4keV. A knowledge of the ionization yield Qy is necessary to establish the trigger threshold of the experiment. The ionization yield Qy is measured in two ways, both in agreement with previous measurements and with a factor of 10 lower energy threshold.

Drilling is one of the key machining operations for manufacturing safety critical components that must comply with strict surface quality standards. The influence of major flank wear of drilling tools on workpiece surface quality has been well established; however, similar information concerning minor cutting edge is currently missing from literature. This paper presents a comprehensive analysis and discussions of the influence of the drill's minor cutting edge to workpiece surface integrity and residual stress distribution for RR1000, a newly developed nickel-based superalloy. These effects are critical to the acceptance of this new material in relation to tool geometry and machining strategies. The thickness of material drag in the hoop direction has been found to be the highest at the top and the least at the bottom of the hole, which is directly related to the contact duration between the minor cutting edge and workpiece surfaces; moreover this difference increased at higher levels of wear of the minor cutting edge. On-line process monitoring techniques have been employed to further understand the material drag phenomena, including feed force, torque and acoustic emission. Compressive axial and tensile hoop stresses at the surface of the holes have been measured as a function of depth and correlated both with metallurgical analysis of drilled surfaces and the process monitoring signals. It was found that the increased material drag associated with a worn tool resulted in compressive hoop surface residual stresses near the entrance hole in correspondence with trends in the processed acoustic emission signal. This work suggests that material drag increases with the duration of the minor cutting edge–workpiece interaction such that plastic deformation is the greatest near the drill entrance holes and that process monitoring of the degree of material drag in hoop direction can be practicable.

The use of heat-resistant titanium alloys for the manufacture of gas turbine engines components for aerospace/energy applications has become a routine exercise. However, components with complex designs specifications might pose manufacturing challenges especially when finishing processes are needed to enable their compliance with tight industrial standards for workpiece surface integrity. Information on polishing processes for such sensitive industrial applications is scarce. The paper reports on the influence of polishing methods/strategies on the quality and integrity of workpiece surfaces obtained after different polishing methods on Ti-6-4 heat-resistant alloy. The research focuses on identifying an “optimised” polishing strategy that will enable finishing a family of targeted safety critical aero-engine (TSCA-E) components, on which the simultaneous fulfillment of the following technological/quality criteria is required: (i) tool life to enable polishing of minimum of workpiece surface areas that are related with specific features of TSCA-E components; (ii) removal of pre-machining (i.e. milling) marks while obtaining required surface finish; (iii) generation of damage-free polished surfaces, i.e. high workpiece surface integrity. Two (belt; bob) polishing methods with various media/grades (Al2O3, SiC, polycrystalline diamond) of the abrasive materials in conjunction with three cutting media (dry; chilled air; minimum quantity of lubricant) have been tested to address the overall finishing of TSCA-E components. Although significant differences in tool life performance exist between belt and bob polishing methods, both are capable to meet the requirements of minimum workpiece surface coverage if “optimised” operating parameters are employed. When considering surface roughness criteria, Al2O3 belts and SiC bob tools were found appropriate. Furthermore, surfaces obtained with these tools when employing cooling media (chilled air for belt polishing and minimum quantity of lubricant (MQL) for bob polishing) showed compliance with the tight requirements of industrial standards for workpiece surface integrity (metallurgical damage and residual stresses). This proved that belt and bob polishing methods can be employed in conjunction as “hybrid” technique to enable automated overall finishing of complex geometrical components.

It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to E-nr=75 keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses m(chi)greater than or similar to 150 GeV are disfavored.