41938556
Short Strips for the sLHC: A P-Type Silicon Microstrip Detector in 3-D Technology
The luminosity upgrade of the Large Hadron Collider (LHC), the sLHC, will constitute an extremely challenging radiation environment for tracking detectors. With respect to the LHC, large improvements in radiation hardness are required. In this paper, we investigated the expected radiation hardness of the 3-D-design, where rows of 3-D-columns are etched in substrate material and joined together to form strips. To investigate the feasibility of 3-D silicon strip detectors (SSD) for the sLHC, we have built prototype modules using 3-D single type column (3-D-STC) strip detectors with short strips and front-end electronics from the present ATLAS SemiConductor Tracker (SCT). The modules were tested with a beta source setup before and after irradiation to sLHC fluences with 26 MeV protons. We report on the performance of these 3-D-modules, compare it to the results prior to irradiation, and draw conclusions about options for using 3-D SSD detectors for tracking at the sLHC.
121972934
Signal and charge collection efficiency of a p-type STC 3D-detector irradiated to sLHC-fluences, read out with 40 MHz
Abstract Using ATLAS SCT front-end electronics, we have built a 3D prototype detector module which was then irradiated to a fluence of 1 × 10 15 n eq / cm 2 . After irradiation, the module was tested with an IR-laser yielding relative CCE measurements with high spatial resolution. Position-sensitive measurements are required, as from simulation the STC 3D-detector geometry is expected to have low-field regions with lower CCE. We report on the performance of the irradiated 3D-module read out at 40 MHz, compare it to the unirradiated behaviour and draw conclusions about the feasibility of using such detectors for tracking at the sLHC.
26356337
Investigation of 3D silicon microstrip detectors for the sLHC
An increase of the luminosity of the Large Hadron Collider (LHC) at CERN is foreseen around 2017 by about an order of magnitude. This will translate into a largely increased radiation dose, with which the present trackers can not cope. The development of radiation-hard silicon detectors is required for the innermost tracking layers. One option for radiation-hard silicon sensors is the 3D technology, where columnar electrodes are etched, perpendicular to the surface, into the silicon bulk. In this paper we investigated 3D single type columns (3D-STC) detectors which were irradiated with 26 MeV protons to fluences up to 2.5×10 15 1-MeV equivalent neutrons(Neq)/cm 2 which corresponds to fluences expected at the inner tracking layers of the sLHC. Before and after irradiations the sensors were tested with a beta-source setup to measure and quantify the radiation induced damage.
120247908
3D stc sensors with different strip isolation schemes and substrate materials
Abstract For the innermost layers of the foreseen upgrade to the ATLAS tracker, charge trapping will be the main limitation in terms of the sensor lifetime. A possible solution to the degradation of the charge collection efficiency (CCE) could be the use of 3D detectors. In 3D detectors the electrodes are processed not just at the surface of the sensor, but they extend partly or completely through the silicon bulk. The distance between the columnar electrodes of 3D detectors can be adjusted to the expected fluence range. We designed and constructed prototype modules comprising ATLAS SCT front-end electronics and 3D single-type column (stc) p-type strip detectors with different strip isolation techniques and different substrate materials. With a strip length of 18.4 mm these sensors could be a radiation hard option for the innermost short strip region of the inner detector in the upgraded ATLAS experiment. We characterised these 3D stc p-type sensors in terms of their noise behaviour and hence their effective capacitance as a function of applied bias voltage at a read-out speed of 40 MHz which is also anticipated for sLHC. Employing an IR laser and automated x – y stages with micrometer resolution we characterised the sensors regarding the CCE in dependence of the bias voltage and the IR laser position relative to the sensors before irradiation.
109469281
3D silicon strip detectors
Abstract While the Large Hadron Collider (LHC) at CERN has started operation in autumn 2008, plans for a luminosity upgrade to the Super-LHC (sLHC) have already been developed for several years. This projected luminosity increase by an order of magnitude gives rise to a challenging radiation environment for tracking detectors at the LHC experiments. Significant improvements in radiation hardness are required with respect to the LHC. Using a strawman layout for the new tracker of the ATLAS experiment as an example, silicon strip detectors (SSDs) with short strips of 2–3 cm length are foreseen to cover the region from 28 to 60 cm distance to the beam. These SSD will be exposed to radiation levels up to 10 15 N eq / cm 2 , which makes radiation resistance a major concern for the upgraded ATLAS tracker. Several approaches to increasing the radiation hardness of silicon detectors exist. In this article, it is proposed to combine the radiation hard 3D-design originally conceived for pixel-style applications with the benefits of the established planar technology for strip detectors by using SSDs that have regularly spaced doped columns extending into the silicon bulk under the detector strips. The first 3D SSDs to become available for testing were made in the Single Type Column (STC) design, a technological simplification of the original 3D design. With such 3D SSDs, a small number of prototype sLHC detector modules with LHC-speed front-end electronics as used in the semiconductor tracking systems of present LHC experiments were built. Modules were tested before and after irradiation to fluences of 10 15 N eq / cm 2 . The tests were performed with three systems: a highly focused IR-laser with 5 μ m spot size to make position-resolved scans of the charge collection efficiency, an Sr 90 β -source set-up to measure the signal levels for a minimum ionizing particle (MIP), and a beam test with 180 GeV pions at CERN. This article gives a brief overview of the results obtained with 3D-STC-modules.
109063356
Laser characterisation of a 3D single-type column p-type prototype module read out with ATLAS SCT electronics
In this paper measurements of a 3D single-type column (3D-stc) microstrip silicon device are shown. The 3D-stc sensor has n-type columns in p-type substrate. It has been connected to an ATLAS SCT ABCD3T chip and is readout with ATLAS SCT electronics at 40 MHz. Spatial measurements were done with a laser setup to investigate the expected low field region in 3D devices. An influence of the p-stops on the collected charge has been observed.
120397395
Measurement of the Helicity Asymmetry of the gamma-p Cross Section Between 2.5 and 5.3 GeV
We report a measurement of the helicity asymmetry of a substantial fraction of the gamma-p total cross section at photon energies between 2.5 and 5.3 GeV in Hall B of Jefferson Lab. The preliminary analysis uses only events with at least one charged particle between approximately 8 and 45 degrees. Assuming that the measured asymmetry applies also to the undetected portion of the cross section, we compare our preliminary result with the results of the Regge parameterization of Bianchi and Thomas.
126279241
Measurement of spin structure functions at moderate Q2 using CLAS
Abstract Spin structure functions of the nucleon in the region of large ξ and small to moderate Q 2 continue to be of high current interest. Among the topics one can study in this kinematic regime are spin-dependent resonance transition amplitudes and their interference with each other and the non-resonant background, the behavior of the asymmetry A 1 at large ξ, and the presence or absence of local duality in spin structure functions. The first moment of the spin structure function g 1 goes through a rapid transition from the photon point ( Q 2 = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. This opens up the possibility to study the transition from hadronic to quark degrees of freedom over the whole range of Q 2 . Recently, we concluded a large experimental program to measure these observables with polarized proton and deuteron targets at Jefferson Lab. A highly polarized electron beam, solid polarized NH 3 and ND 3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to accumulate over 23 billion events with 4 different beam energies of 1.6, 2.5, 4.2 and 5.7 GeV. We present an overview of the experiment, its kinematic coverage and its statistical power. We show final results from the first run at 2.5 GeV and 4 GeV and preliminary results from the 5.7 GeV and the 1.6 GeV data sets.
7834320
MEASUREMENTS OF THE NUCLEON FORM FACTORS AT LARGE MOMENTUM TRANSFERS
New measurements of the electric GE(Q2) and magnetic GM(Q2) form factors of the nucleons are reported. The proton data cover the Q2 range from 1.75 to 8.83 (GeV/c)2 and the neutron data from 1.75 to 4.00 (GeV/c)2, more than doubling the range of previous data. Scaled by the dipole fit, GD(Q2), the results forGMp(Q2) /?pGD(Q2) decrease smoothly from 1.05 to 0.92, while GEp(Q2)/GD(Q2)is consistent with unity. The preliminary results for GMn(Q2) /?nGD(Q2) are consistent with unity, while GEn is consistent with zero at all values of Q2.
121581138
Inclusive asymmetries and spin structure functions of the nucleon