T. Koeth

Status of the R&D activity on diamond particle detectors

Chemical Vapor Deposited (CVD) polycrystalline diamond has been proposed as a radiation-hard alternative to silicon in the extreme radiation levels occurring close to the interaction region of the Large Hadron Collider. Due to an intense research effort, reliable high-quality polycrystalline CVD diamond detectors, with up to 270μm charge collection distance and good spatial uniformity, are now available. The most recent progress on the diamond quality, on the development of diamond trackers and on radiation hardness studies are presented and discussed.

First observation of the exchange of transverse and longitudinal emittances

An experimental program to demonstrate a novel phase-space manipulation in which the horizontal and longitudinal emittances of a particle beam are exchanged has been completed at the Fermilab A0 Photoinjector. A new beam line, consisting of a TM(110) deflecting mode cavity flanked by two horizontally dispersive doglegs has been installed. We report on the first direct observation of transverse and longitudinal emittance exchange.

CVD diamond sensors for charged particle detection

Abstract CVD diamond material was used to build position-sensitive detectors for single-charged particles to be employed in high-intensity physics experiments. To obtain position information, metal contacts shaped as strips or pixels are applied to the detector surface for one- or two-dimensional coordinate measurement. Strip detectors 2×4 cm2 in size with a strip distance of 50 μm were tested. Pixel detectors of various pixel sizes were bump bonded to electronics chips and investigated. A key issue for the use of these sensors in high intensity experiments is the radiation hardness. Several irradiation experiments were carried out with pions, protons and neutrons exceeding a fluence of 1015 particles/cm2. The paper presents an overview of the results obtained with strip and pixel detectors in high-energy test beams and summarises the irradiation studies.

Performance of irradiated CVD diamond micro-strip sensors

Abstract CVD diamond detectors are of interest for charged particle detection and tracking due to their high radiation tolerance. In this article, we present, for the first time, beam test results from recently manufactured CVD diamond strip detectors and their behavior under low doses of electrons from a β-source and the performance before and after intense (>10 15 /cm 2 ) proton- and pion-irradiations. We find that low dose irradiation increase the signal-to-noise ratio (pumping of the signal) and slightly deteriorate the spatial resolution. Intense irradiation with protons 2.2×10 15 p / cm 2 lowers the signal-to-noise ratio slightly. Intense irradiation with pions 2.9×10 15 π / cm 2 lowers the signal-to-noise ratio more. The spatial resolution of the diamond sensors improves after irradiations.

Micro-strip sensors based on CVD diamond

Abstract In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Longitudinal confinement and matching of an intense electron beam

An induction cell has successfully been demonstrated to longitudinally confine a space-charge dominated bunch for over a thousand turns (>11.52 km) in the University of Maryland Electron Ring [Haber et al., Nucl. Instrum. Methods Phys. Res. A 606, 64 (2009) and R. A. Kishek et al., Int. J. Mod. Phys. A 22, 3838 (2007)]. With the use of synchronized periodic focusing fields, the beam is confined for multiple turns overcoming the longitudinal space-charge forces. Experimental results show that an optimum longitudinal match is obtained when the focusing frequency for containment of the 0.52 mA beam is applied at every fifth turn. Containment of the beam bunch is achievable at lower focusing frequencies, at the cost of a reduction in the transported charge from the lack of sufficient focusing. Containment is also obtainable, if the confinement fields overfocus the bunch, exciting multiple waves at the bunch ends, which propagate into the central region of the beam, distorting the overall constant current beam...

New results on diamond pixel sensors using ATLAS frontend electronics

Abstract Diamond is a promising sensor material for future collider experiments due to its radiation hardness. Diamond pixel sensors have been bump bonded to an ATLAS pixel readout chip using PbSn solder bumps. Single chip devices have been characterised by lab measurements and in a high-energy pion beam at CERN. Results on charge collection, spatial resolution, efficiency and the charge carrier lifetime are presented.

Beam test results of the US-CMS forward pixel detector

Abstract CMS will use silicon pixel as its innermost tracking device. Prototypes of these 150 μm square pixels bump bonded to DMILL readout chips were tested at CERN in a pion beam. A silicon telescope consisting of 8 planes of silicon strips was used to interpolate tracks to the position of the pixel detector. Data were taken with the beam at different angles of incidence relative to the pixel sensors. Position resolutions between 10 and 20 μm , depending on the hit position, were observed using charge sharing for the final configuration with unirradiated detectors. The observed resolution was as expected.

CVD diamond pixel development

Pixel detectors using synthetic diamond are an attractive alternative to silicon for use in radiation harsh environments such as at the Large Hadron Collider (LHC). Recent test beam results using Compact Muon Solenoid pixel readout electronics are presented, which demonstrate a hit efficiency of 95% and position resolution of 31 /spl mu/m for a diamond pixel sensor with 125 /spl times/ 125 /spl mu/m/sup 2/ pitch.

Capture cavity II results at FNAL

As part of the research and development towards the International Linear Collider (ILC), several test facilities have been developed at Fermilab. This paper presents the latest Low Level RF (LLRF) results obtained with Capture Cavity II (CCII) at the ILC Test Accelerator (ILCTA) test facility. The main focus will be on controls and RF operations using the SIMCON based LLRF system developed in DESY. Details about hardware upgrades and future work will be discussed.