J. Thornhill

The GREAT triggerless total data readout method

Recoil decay tagging (RDT) is a very powerful method for the spectroscopy of exotic nuclei. RDT is a delayed coincidence technique between detectors usually at the target position and at the focal plane of a spectrometer. Such measurements are often limited by dead time. This paper describes a novel triggerless data acquisition method, which is being developed for the Gamma Recoil Electron Alpha Tagging (GREAT) spectrometer, that overcomes this limitation by virtually eliminating dead time. Our solution is a total data readout (TDR) method where all channels run independently and are associated in software to reconstruct events. The TDR method allows all the data from both target position and focal plane to be collected with practically no dead-time losses. Each data word is associated with a timestamp generated from a global 100-MHz clock. Events are then reconstructed in real time in the event builder using temporal and spatial associations defined by the physics of the experiment.

Digital gamma-ray tracking algorithms in segmented germanium detectors

A gamma-ray tracking algorithm has been implemented and tested, using simulated data, for gamma rays with energies between 0.1 and 2 MeV, and its performance evaluated for a 90-mm-long, 60-mm-diameter, cylindrical, 36 (6 /spl times/ 6) segment detector. The performance of the algorithm in two areas was determined: Compton suppression and Doppler shift correction. It was found that for gamma rays of energies around 1 MeV, a ratio of photopeak counts to total counts of 2:3 could be obtained using the tracking algorithm, with only a 2% reduction in detection efficiency, compared to the untracked data. Approximately 80% of first interaction points could be correctly identified, enabling a good Doppler shift correction. A detector of the type simulated has recently been delivered, together with a compactPCI digital data acquisition system comprising 36 12-bit, 40-MHz flash ADCs, and 6200-MHz DSPs. Some initial data has been recorded using this system, and the performance of the tracking algorithm on this real data is comparable to its performance on simulated data.

Towards combining in‐beam γ‐ray and conversion electron spectroscopy

The SAGE spectrometer will combine a segmented Si‐detector with a Ge‐detector array aiming to take the simultaneous in‐beam γ‐ray and conversion electron spectroscopy to the next level. It will be coupled with the GREAT focal plane spectrometer and the RITU gas‐filled recoil separator at the accelerator laboratory of the University of Jyvaskyla, Finland. Its high efficiency and resolution will open the door to a new era of complete spectroscopy directed, amongst others, at the study of superheavy nuclei aiming to investigate the properties of the next spherical proton shell above Zu2009=u200982.

The ALPHA – detector: Module Production and Assembly

ALPHA is one of the experiments situated at CERNs Antiproton Decelerator (AD). A Silicon Vertex Detector (SVD) is placed to surround the ALPHA atom trap. The main purpose of the SVD is to detect and locate antiproton annihilation events by means of the emitted charged pions. The SVD system is presented with special focus given to the design, fabrication and performance of the modules.

The SAGE spectrometer: A tool for combined in-beam γ-ray and conversion electron spectroscopy

The SAGE spectrometer allows simultaneous in-beam γ-ray and internal conversion electron measurements, by combining a germanium detector array with a highly segmented silicon detector and an electron transport system. SAGE is coupled with the ritu gas-filled recoil separator and the great focal-plane spectrometer for recoil-decay tagging studies. Digital electronics are used both for the γ ray and the electron parts of the spectrometer. SAGE was commissioned in the Accelerator Laboratory of the University of Jyvaskyla in the beginning of 2010.

The Delphi outer detector

Abstract The design criteria, construction and performance of the Delphi outer detector are discussed. The detector is a 5-layer, 5 m long, 2 m inner radius, 2.1 m outer radius “cylindrical” drift chamber consisting of 3480 individual 1.65 × 1.65 cm 2 drift tubes operating in limited streamer mode. The drift time-distance relationship for a single tube has been measured using a pulsed laser as a function of both track angle and longitudinal magnetic field. These data have been used to reconstruct cosmic rays in a completed detector module and yield a transverse resolution of 80 μ m per point over most of the cell, rising to 90 μ m near the corners of the tubes. The detection efficiency per cell for minimum ionising particles is greater than 98.5%.

The SPEDE spectrometer

Abstract.The electron spectrometer, SPEDE, has been developed and will be employed in conjunction with the Miniball spectrometer at the HIE-ISOLDE facility, CERN. SPEDE allows for direct measurement of internal conversion electrons emitted in-flight, without employing magnetic fields to transport or momentum filter the electrons. Together with the Miniball spectrometer, it enables simultaneous observation of

A 128-channel event driven readout ASIC for the R3B tracker

gamma

TRANSMISSION EFFICIENCY OF THE SAGE SPECTROMETER USING GEANT4

γ rays and conversion electrons in Coulomb excitation experiments using radioactive ion beams.

Construction and beam test results for the DELPHI two metre straw detector

R3B is a detector with high efficiency, acceptance, and resolution for kinematically complete measurements of reactions with high-energy radioactive beams. Detectors track and identify radioactive beams into and out of a reaction target. Three layers of double-sided stereoscopic silicon strips form the tracker detector which must provide precise tracking and vertex determination and in addition include energy and multiplicity measurements. The R3B ASIC has been manufactured and is intended for processing and digitising signals generated by ionising particles passing through the tracker. The ASIC processes signals and provides spatial, energy and time measurements.