Diamond Beam Monitor Research Articles

Test beam results of ATLAS DBM pCVD diamond detectors using a novel threshold tuning method

Threshold Baseline Tuning is a novel threshold tuning method meant to increase the hit efficiency of a pixel detector. The tuning method is applicable to any pixel readout ASIC with an adjustable threshold for individual pixels. The method is based on counting noise hits and allows for tuning to very low thresholds. The Threshold Baseline Tuning was successfully tested with ATLAS Diamond Beam Monitor (DBM) polycrystalline chemical vapour deposited (pCVD) diamond detectors in a 120 GeV pion beam at CERN SPS in 2015/2016. Efficiency measurements show the advantage of the Threshold Baseline Tuning over the regular tuning method.

Diamond Pixel Detectors and 3D Diamond Devices

Results from detectors of poly-crystalline chemical vapour deposited (pCVD) diamond are presented. These include the first analysis of data of the ATLAS Diamond Beam Monitor (DBM). The DBM module consists of pCVD diamond sensors instrumented with pixellated FE-I4 front-end electronics. Six diamond telescopes, each with three modules, are placed symmetrically around the ATLAS interaction point. The DBM tracking capabilities allow it to discriminate between particles coming from the interaction point and background particles passing through the ATLAS detector. Also, analysis of test beam data of pCVD DBM modules are presented. A new low threshold tuning algorithm based on noise occupancy was developed which increases the DBM module signal to noise ratio significantly. Finally first results from prototypes of a novel detector using pCVD diamond and resistive electrodes in the bulk, forming a 3D diamond device, are discussed. 3D devices based on pCVD diamond were successfully tested with test beams at CERN. The measured charge is compared to that of a strip detector mounted on the same pCVD diamond showing that the 3D device collects significantly more charge than the planar device.

The upgraded Pixel Detector of the ATLAS Experiment for Run 2 at the Large Hadron Collider

During Run 1 of the Large Hadron Collider (LHC), the ATLAS Pixel Detector has shown excellent performance. The ATLAS collaboration took advantage of the first long shutdown of the LHC during 2013 and 2014 and extracted the ATLAS Pixel Detector from the experiment, brought it to surface and maintained the services. This included the installation of new service quarter panels, the repair of cables, and the installation of the new Diamond Beam Monitor (DBM). Additionally, a completely new innermost pixel detector layer, the Insertable B-Layer (IBL), was constructed and installed in May 2014 between a new smaller beam pipe and the existing Pixel Detector. With a radius of 3.3cm the IBL is located extremely close to the interaction point. Therefore, a new readout chip and two new sensor technologies (planar and 3D) are used in the IBL. In order to achieve best possible physics performance the material budget was improved with respect to the existing Pixel Detector. This is realized using lightweight staves for mechanical support and a CO2 based cooling system.This paper describes the improvements achieved during the maintenance of the existing Pixel Detector as well as the performance of the IBL during the construction and commissioning phase. Additionally, first results obtained during the LHC Run 2 demonstrating the distinguished tracking performance of the new Four Layer ATLAS Pixel Detector are presented.

ATLAS Pixel Detector ROD card from IBL towards Layers 2 and 1

The incoming and future upgrades of LHC will require better performance by the data acquisition system, especially in terms of throughput due to the higher luminosity that is expected. For this reason, during the first shutdown of the LHC collider in 2013/14, the ATLAS Pixel Detector has been equipped with a fourth layer— the Insertable B-Layer or IBL—located at a radius smaller than the present three layers. To read out the new layer of pixels, with a smaller pixel size with respect to the other outer layers, a front end ASIC (FE-I4) was designed as well as a new off-detector read-out chain. The latter, accordingly to the structure of the other layers of pixels, is composed mainly of two 9U-VME read-out off-detector cards called the Back-Of-Crate (BOC) and Read-Out Driver (ROD). The ROD is used for data and event formatting and for configuration and control of the overall read-out electronics. After some prototyping samples were completed, a pre-production batch of 5 ROD cards was delivered with the final layout. Another production of 15 ROD cards was done in Fall 2013, and commissioning was completed in 2014. Altogether 14 cards are necessary for the 14 staves of the IBL detector, one additional card is required by the Diamond Beam Monitor (DBM), and additional spare ROD cards were produced for a total initial batch of 20 boards. This paper describes some integration tests that were performed and our plan to install the new DAQ chain for the layer 2, which is the outermost, and layer 1, which is external to the B-layer. This latter is the only layer that will not be upgraded to a higher readout speed. Rather, it will be switched off in the near future as it has too many damaged sensors that were not possible to rework. To do that, slices of the IBL read-out chain have been instrumented, and ROD performance is verified on a test bench mimicking a small-sized final setup. Thus, this contribution reports also how the adoption of the IBL ROD for ATLAS Pixel Detector Layer 2 was developed, with the production of other 40 boards completed and tested in 2015, and how the same approach will be used for the production of the last 45 ROD boards for the Layer 1. This latter fabrication has started on Fall 2015.

The ATLAS Diamond Beam Monitor: Luminosity detector at the LHC

After the first three years of the LHC running, the ATLAS experiment extracted its pixel detector system to refurbish and re-position the optical readout drivers and install a new barrel layer of pixels. The experiment has also taken advantage of this access to install a set of beam monitoring telescopes with pixel sensors, four each in the forward and backward regions. These telescopes are based on chemical vapor deposited (CVD) diamond sensors to survive in this high radiation environment without needing extensive cooling. This paper describes the lessons learned in construction and commissioning of the ATLAS Diamond Beam Monitor (DBM). We show results from the construction quality assurance tests and commissioning performance, including results from cosmic ray running in early 2015.

Diamond particle detectors systems in high energy physics

With the first three years of the LHC running complete, ATLAS and CMS are planning to upgrade their innermost tracking layers with more radiation hard technologies. Chemical Vapor Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. The lessons learned in constructing the ATLAS Beam Conditions Monitor (BCM), Diamond Beam Monitor (DBM) and the CMS Pixel Luminosity Telescope (PLT) all of which are based on CVD diamond with the goal of elucidating the issues that should be addressed for future diamond based detector systems. The first beam test results of prototype diamond devices with 3D detector geometry should further enhance the radiation tolerance of this material.

Commissioning of the read-out driver (ROD) card for the ATLAS IBL detector and upgrade studies for the pixel Layers 1 and 2

The higher luminosity that is expected for the LHC after future upgrades will require better performance by the data acquisition system, especially in terms of throughput. In particular, during the first shutdown of the LHC collider in 2013/14, the ATLAS Pixel Detector will be equipped with a fourth layer – the Insertable B-Layer or IBL – located at a radius smaller than the present three layers. Consequently, a new front end ASIC (FE-I4) was designed as well as a new off-detector chain. The latter is composed mainly of two 9U-VME cards called the Back-Of-Crate (BOC) and Read-Out Driver (ROD). The ROD is used for data and event formatting and for configuration and control of the overall read-out electronics. After some prototyping samples were completed, a pre-production batch of 5 ROD cards was delivered with the final layout. Actual production of another 15 ROD cards is ongoing in Fall 2013, and commissioning is scheduled in 2014. Altogether 14 cards are necessary for the 14 staves of the IBL detector, one additional card is required by the Diamond Beam Monitor (DBM), and additional spare ROD cards will be produced for a total of 20 boards. This paper describes some integration tests that were performed and our plan to test the production of the ROD cards. Slices of the IBL read-out chain have been instrumented, and ROD performance is verified on a test bench mimicking a small-sized final setup. This contribution will report also one view on the possible adoption of the IBL ROD for ATLAS Pixel Detector Layer 2 (firstly) and, possibly, in the future, for Layer 1.

Synchronized analysis of testbeam data with the Judith software

The Judith software performs pixel detector analysis tasks utilizing two different data streams such as those produced by the reference and tested devices typically found in a testbeam. This software addresses and fixes problems arising from the desynchronization of the two simultaneously triggered data streams by detecting missed triggers in either of the streams. The software can perform all tasks required to generate particle tracks using multiple detector planes: it can align the planes, cluster hits and generate tracks from these clusters. This information can then be used to measure the properties of a particle detector with very fine spatial resolution. It was tested at DESY in the Kartel telescope, a silicon tracking detector, with ATLAS Diamond Beam Monitor modules as a device under test.

The ATLAS Diamond Beam Monitor

The ATLAS Diamond Beam Monitor is a novel charged-particle detector. It will be used in the ATLAS experiment to measure luminosity and beam background. The monitor's pCVD diamond sensors are instrumented with pixellated FE-I4 front-end chips. The CVD diamond sensor material was chosen to ensure long-term durability of the sensors in a radiation-hard environment. This document describes the principles of luminosity measurements. It then explains how the Diamond Beam Monitor will carry out this task.

X-ray beam monitor made by thin-film CVD single-crystal diamond

A novel beam position monitor, operated at zero bias voltage, based on high-quality chemical-vapor-deposition single-crystal Schottky diamond for use under intense synchrotron X-ray beams was fabricated and tested. The total thickness of the diamond thin-film beam monitor is about 60 µm. The diamond beam monitor was inserted in the B16 beamline of the Diamond Light Source synchrotron in Harwell (UK). The device was characterized under monochromatic high-flux X-ray beams from 6 to 20 keV and a micro-focused 10 keV beam with a spot size of approximately 2 µm × 3 µm square. Time response, linearity and position sensitivity were investigated. Device response uniformity was measured by a raster scan of the diamond surface with the micro-focused beam. Transmissivity and spectral responsivity versus beam energy were also measured, showing excellent performance of the new thin-film single-crystal diamond beam monitor.