Silicon Detector Array (SIDAR)
The Silicon Detector Array
(SIDAR) is a collection of single-sided silicon strip detectors for
experiments in nuclear astrophysics and nuclear physics. It
offers high granularity, excellent energy resolution, and good
resolution in position, angle, and timing.
The array can be configured in a variety of arrangements within a dedicated target chamber with the
limiting factors of geometry and the number of electronics channels
can be stored simultaneously. We are currently limited to about
256 channels. Detector signals are usually read from the p-type
strips, however, it is also possible to read out just the n-type pad
reducing the number of channels at the cost of resolution and position
information. Amplification is performed using 8-channel amplifiers/discriminators
from Rutherford Appleton Laboratory where the gains
are set using
plug-in resistor chips and a common threshold per module. Peak
sensing 8-channel CAMAC ADCs originally developed by Silena
are used to digitize the peak heights with the count rate limited to
about 2 kHz. We have also used faster VME ADCs from CAEN
which allow for count rates up to about 7 kHz.|
We have available a variety of geometry and thickness detectors all purchased from Micron Semiconductor. The original system was modeled after the Louvain-Edinburgh Detector Array (LEDA) and was composed of YY1 design detectors.
Eight of the YY1 detectors can be arranged in a flat annular array with sixteen 0.5-cm strips covering radii from 5 to 13 cm. Six detectors can also be configured in a "lampshade" arrangement to cover a larger angular range. The quantity and thicknesses of available YY1 detectors are listed below.
Other smaller annular detectors are also available including two S1-style 300 micron thick detectors with 4 quadrants of 16 rings subtending radii from 2.4 to 4.8 cm in 1.5 mm strips and one S2-style 300 micron thick detector with 48 rings subtending radii from 1.1 to 3.5 cm in 0.5 mm strips. The S-style detectors are good complements to the YY1 detectors when detection of particles over most of the forward or backward hemispheres is required.
In addition to the annular detectors, we have several styles and thicknesses of rectangular 5cm X 5cm pad and strip detectors.
The strip detectors are divided into 16 strips (5cm X 0.3 cm), and some are position-sensitive where the position along the strip is determined via charge division with resolution ~ 1 mm. The quantity and thicknesses that we have available are listed below.
The SIDAR array has been used for a variety of radioactive ion beam [1-10] and stable beam experiments [11-12]. As a result of the large solid angle coverage and segmentation of the array, it naturally lends itself to making kinematically-complete measurements such as the 1H(18F,alpha)15O measurement pictured below.
From left to right: The experimental setup for the 1H(18F,alpha)15O measurement is shown. The 18F/18O beam impinged on a CH2 target.15O ions and alpha particles were detected in the SIDAR array configured in lampshade mode. The middle picture shows by plotting the a energy vs. the heavy recoil energy, the events of interest were clearly identified. The right picture shows the excitation functions measured for 1H(18F,alpha)15O and 1H(18F,p)18F by stepping the beam energy through a resonance of interest.
The range of thicknesses of detectors makes particle identification possible while still simultaneously measuring the energy and angular distributions of reaction products. A typical particle identification spectrum measured in a study of the 2H(18F,n)19Ne* reaction is shown below.
In addition to the SIDAR array, we are currently working on a next generation silicon array (ORRUBA) optimized for detection of charged particles near 90 degrees in the laboratory.
The SIDAR array was developed by the RIBENS collaboration involving researchers from multiple institutions including ORNL, Tennessee Technological University, Rutgers University, Yale University, University of North Carolina at Chapel Hill, University of Edinburgh, and Colorado School of Mines.
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This file last modified Tuesday September 25, 2007