Stripixel Detector Research Articles

Laser test studies on the single-sided dual-column 3D stripixelsilicon detector

The single-sided full-3D stripixel detector and the laser test system were introduced in this paper. The detector responses to different conditions (including detector bias voltage, laser illumination position, pulse generator parameters setting for driving laser device, etc) were measured and analyzed. Main detector parameters, including the depletion voltage, 2D position sensitivity response, charge collection characteristics with different bias voltages, noise distribution characteristics influenced by the different coupling modes of n+-strips and p+-strips electrodes to the readout chip channels, were obtained with 1060nm laser irradiation tests. The measurement results showed that the detector was position sensitive. Its depletion voltage was about 5V. The measured equivalent noise charge(ENC) of the detector system was about 730±10e.

Design, fabrication and characterization of the first dual-column 3D stripixel detectors

This paper presents design, fabrication and the first characterization of the new 3D stripixel detector. The device has dual-column electrodes (both n+- and p+-type) arranged in a quincunx configuration and processed in a single-sided process on n-type silicon bulk. Double-metal technology allows to connect the electrodes by two sets of perpendicular strips providing a X-Y projective read-out. The design of the sensor has been optimized with the use of TCAD Sentaurus simulations. TCT measurements were performed to study the active area of the detector. Finally, 2D position sensitivity was investigated reconstructing the position of a laser beam within a 80 × 80 μm2 pixel, defined by two neighbouring p+-type strips crossing two neighbouring n+-type strips.

Status and Performance of New Silicon Stripixel Detector for the PHENIX Experiment at RHIC: Beta Source, Cosmic-rays and Proton Beam at 120 GeV

We are constructing a Silicon Vertex Tracker detector (VTX) for the PHENIX experiment at RHIC. Our main motivation is to enable measurements of heavy flavor production (charm and beauty) in p+p, p+d and A+A collisions. Such data will illuminate the properties of the matter created in high-energy heavy-ion collisions. The measurements also will reveal the distribution of gluons in protons from p+p collisions. The VTX detector consists of four layers of barrel detectors and covers |η|<1.2, and almost a 2π in azimuth. The inner two silicon barrels consist of silicon pixel sensors; their technology accords with that of the ALICE1LHCB sensor-readout hybrid. The outer two barrels are silicon stripixel detectors with a new ``spiral'' design, and a single-sided sensor with 2-dimensional (X, U) readout. In this paper, we describe the silicon stripixel detector and discuss its performance, including its response to electrons from a beta source (90Sr), muons from cosmic-rays, and a 120 GeV proton beam. The results from the proton beam demonstrate that the principle of two-dimensional position sensitivity based on charge sharing works; the signal-to-noise value is 10.4, the position resolution is 33.6 μm for X-stripixel (35.2 μm for U-stripixel), and the tracking efficiencies in the X- and U-stripixels are, over 98.9±0.2%. The stripixel detector within the VTX project is in the pre-production phase.

Fine Pitch and Low Material Readout Bus for the Silicon Pixel Detector in the PHENIX Vertex Tracker

The silicon pixel detector will be installed in summer 2009 as part of the RHIC-PHENIX silicon vertex tracker (VTX) upgrade at the Brookhaven National Laboratory. The VTX consists of a silicon pixel detector and stripixel detector. For the construction of the silicon pixel detector, we have developed a fine pitch and low material readout bus as the backbone parts of the VTX. In this article, we report the development of the readout bus.

PHENIX upgrade: Novel stripixel detector for heavy quark detection and proton spin structure measurements at RHIC energies

New design of silicon stripixel sensor has been developed at BNL for PHENIX upgrade. The sensor is a single-sided, DC-coupled, two-dimensional position sensitive device with good position resolution. This design is simpler for sensor fabrication and signal processing than the conventional double-sided strip sensor. HPK has produced pre-production stripixel sensors with thickness of 625μm. The quality assurance tests show that the very low leakage current 0.12nA per strip allows the use of the SVX4 chip. A long term stability test shows that the leakage current is stable over a long period of time. The study of the effects of irradiation on the performance of the stripixel sensor has been made using p+p collisions at 200GeV at PHENIX, 14MeV neutron and 20MeV proton beams.

First large scale application of novel Si stripixel detector in real large experiment: Si VTX in PHENIX upgrade at RHIC

2D position sensitive, single-sided Si stripixel detector was selected as the one of the two main components of the Sivertex tracker (Si SVX) in the upgraded PHENIX detector at RHIC (relativistic heavy ion collider) in Brookhaven National Laboratory (BNL). This is the first large scale application of the novel Si stripixel detector in a real large experiment after many years of research and development at BNL. The first and second prototype fabrication runs of the SVX stripixel detectors were carried out successfully in BNL's Si detector development and processing Lab. The processing of these stripixel detectors is similar to that for the standard single-sided strip detectors: one-sided processing, single implant for the pixel (strip) electrodes, etc. The only additional processing step is the double metal process, a technology that is simple and well matured by many Si detector processing industries and labs, including BNL. The laser and beam tests on those prototype detectors show the 2D position sensitivity and good position resolution in both X and U coordinates (about 25 μm for 80 μm pitch). For the mass production of 400 sensors needed for the Si SVX, the processing technology has been successfully transferred to the industrial: Hamamatsu Photonics (HPK). HPK has produced a pre-production run of stripixel sensors with the full PHENIX SVX specification on 150 mm diameter wafers. The laser tests on these pre-production wafers show good signal to noise ratio (about 20:1).

Development and testing of novel stripixel detectors for the silicon vertex tracker at PHENIX

As a part of the upgrades for the PHENIX detector at RHIC,a silicon vertex tracking detector is planned. This detector will consist of two pixel layers followed by two strip-pixel layers in the barrel region,an d four mini-strip layers in the endcap region. As a part of the development phase of the vertex detector, we have set up three sensor testing facilities at Brookhaven National Laboratory, at State University of New York, Stonybrook, and at University of New Mexico to characterize the preproduction sensors, and develop our testing and quality assurance plans. Preliminary results from these test are presented here.

Electron beam and laser testing on the novel stripixel detectors

The novel Si stripixel detector, developed at BNL (Brookhaven National Laboratory), has been applied in the development of a prototype Si strip detector system for the PHENIX Upgrade at RHIC. The Si stripixel detector can generate X – Y two-dimensional (2D) position sensitivity with single-sided processing and readout. Test stripixel detectors with pitches of 85 and 560 μm have been subjected to the electron beam test in a SEM set-up, and to the laser beam test in a lab test fixture with an X – Y – Z table for laser scanning. Test results have shown that the X and Y strips are well isolated from each other, and 2D position sensitivity has been well demonstrated in the novel stripixel detectors.

Development of 2nd prototype of novel silicon Stripixel detector for PHENIX upgrade

Development of 2nd prototype of novel silicon Stripixel detector for PHENIX upgrade

Development of a novel silicon stripixel detector for RHIC-PHENIX detector upgrade

A new single-sided silicon strip detector has been developed for the silicon vertex tracker of the PHENIX detector at the Relativistic Heavy Ion Collider in Brookhaven National Laboratory (BNL). The novel "stripixel" detector concept developed by the BNL Instrumentation Division was applied to the first prototype silicon sensor. The novel feature of the stripixel concept is two-dimensional (2-D) position sensitivity with single-sided processing achieved by charge sharing between two interleaved electrodes in one pixel. Signals are read out projectively by double layers of aluminum strips. The first prototype stripixel sensors with the size of 34.3 /spl times/ 64.6 mm and thickness of 250 and 400 /spl mu/m were fabricated. The detector with readout electronics was constructed to evaluate the prototype sensor performance by using an analog multiplexer chip with charge sensitive preamplifier-shaper circuits (VA2 chip of IDEAS). The sensor performance on charge sharing, detection efficiency, signal-to-noise ratio, and position resolution has been tested with a radioactive source and a GeV particle beam at KEK-PS. The stripixel detector concept, the specification of the first prototype stripixel sensor, and the test results are presented.

Development of 2nd prototype of novel silicon Stripixel detector for PHENIX upgrade

A novel detector type, named “Stripixel” detector developed at BNL, has been applied in the development of a prototype Si strip detector system for the PHENIX Upgrade at RHIC. This novel detector type can generate X- Y two-dimensional position sensitivity with single-sided processing and readout. The prototype Si Stripixel detector has an active area of about 3 cm × 6 cm, which is divided into two identical halves. Both X and Y pitches are 80 μm, with a stereo angle of 4.6°. There are 384 X strips and 384 Y strips on each half of the detector. The first prototype Si Stripixel detectors have been produced at BNL. The initial tests of detector properties have yielded good results on position resolution in both X and Y coordinates. The design and mask set production of the 2nd prototype Si strip detectors were completed in December 2003. In the 2nd prototype design, the maximum distance between the X and Y interleaving pixels is shortened significantly to solve the asymmetry in charge sharing between X and Y pixels and strips observed in the first prototype Stripixel detectors. Also, a novel pixel inter-connection scheme with overlapping pixels is implemented, which can generate the same position resolution with twice of the pitch size as in the tradition scheme. In this novel scheme, for the same position resolution, one may just use half of the number of strips (in a given detector size), thus saving the readout channels by a factor of two. The first batch of the fabrication run of the 2nd prototype Stripixel detectors have been completed in February 2004. Preliminary electrical tests have revealed good results. Laser, source and beam tests are planned.

Novel silicon stripixel detector for PHENIX Upgrade

Novel detector type, named “Stripixel” detector developed at BNL, has been applied in the development of a prototype Si strip detector for the PHENIX Upgrade at RHIC. This novel detector type can generate X– Y two-dimensional position sensitivity with single-sided processing and readout. The prototype Si stripixel detector has an active area of about 3 cm×6 cm, which is divided into two identical halves. Both X and Y pitches are 80 μm, with a stereo angle of 4.6°. There are 384 X strips and 384 Y strips on each half of the detector. The first batch of prototype Si stripixel detectors has been produced at BNL. The initial tests of detector electrical properties have yielded good results. Charge collection tests on test-structure strip detectors have shown both X and Y position sensitivities to laser light. Beam tests on the Si strip detectors have been done at RIKEN in November 2002.

Novel silicon stripixel detector: concept, simulation, design, and fabrication

A novel detector concept has been developed in this work that has the necessary properties to provide two-dimensional (2-D) position sensitivity with a moderate number of readout electronic channels and single-sided detector fabrication process. The concept is based on interleaved pixel electrodes arranged in a projective X– Y readout, which makes possible position encoding with minimum number of channels. In further discussions, we refer to this concept as “stripixel” detector, as it combines the 2-D position resolution of a pixel electrode geometry with the simplicity of the projective readout of a double-sided strip detector. For DC coupled detectors with large pitches (>20 μm), individual pixels are divided into X- and Y-cell that can be interleaved by many different schemes that ensure the charge sharing between them. This type of stripixel detectors is called interleaved stripixel detectors. When the detector pitch goes down (<20 μm), the X and Y-pixel may not have to be interleaved, and they can be connected in an alternating way to X– Y strip readout. This type of stripixel detectors is called alternating stripixel detectors (ASD). For ASD, a position resolution better than 1 μm in two dimensions can be achieved by determining the centroid of the charge collected on pixel electrodes with a granularity in the range of 5–6 μm. For AC coupled detectors, no interleaving scheme may be needed, and there may be no limit on the pitch size, i.e. it may go from pitches in the order of microns, to hundreds of microns or even mm's. This electrode granularity does not pose difficult demands on the lithography and the fabrication technology. This novel detector concept can be applied to any semiconductor detectors/sensors, such as Si, Ge, GaAs, SiC, diamond, etc.