First measurements of beam backgrounds at SuperKEKB Lewis, P.M.; Jaegle, I.; Nakayama, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2019, Letnik:
914
Journal Article
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Odprti dostop
The high design luminosity of the SuperKEKB electron–positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and ...mitigating these backgrounds is critical to the success of the Belle II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam–gas, Touschek, beam–dust, and injection backgrounds. As there is no final focus of the beams in Phase 1, we do not observe significant synchrotron radiation, as expected. Measured LER beam–gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam–gas backgrounds are on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1–2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB.
Artificially-grown diamond crystals have unique properties that make them suitable as solid-state particle detectors and dosimeters in high-radiation environments. We have been using sensors based on ...single-crystal diamond grown by chemical vapour deposition for dosimetry and beam-loss monitoring at the SuperKEKB collider. Here we describe the assembly and the suite of test and calibration procedures adopted to characterise the diamond-based detectors of this monitoring system. We report the results obtained on 28 detectors and assess the stability and uniformity of response of these devices.
Owing to its excellent radiation hardness, diamond has been widely used for solid-state particle detectors and dosimeters in harsh radiation environments. In order to assess the crystal quality and ...the response of our devices, we carried out several tests using different radiation sources. We devised a current-to-dose-rate calibration method that employs a silicon diode as a reference, to greatly reduce uncertainties associated with the source activity and with the setup simulation. The method has been validated by measuring the calibration factors with X and β radiation, spanning a dose-rate range from hundreds of nrad/s to tens of rad/s. Here we report the results for a set of tests and calibrations performed on ten new diamond detectors recently assembled and tested. The new results include several refinements of the measurements and of their interpretation. We also briefly describe an ongoing irradiation of the devices with 1-GeV electrons from the linac of the FERMI@Elettra FEL in Trieste.
Thin pixel development for the SuperB silicon vertex tracker Rizzo, G.; Avanzini, C.; Batignani, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2011, Letnik:
650, Številka:
1
Journal Article
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The high luminosity SuperB asymmetric
e
+
e
−
collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10
36
cm
−2
s
−1 with ...moderate beam currents and a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5
cm), resolution of
10
–
15
μ
m
in both coordinates, low material budget (
<
1
%
X0), and able to withstand a background rate of several tens of MHz/cm
2. The ambitious goal of designing a thin pixel device with these stringent requirements is being pursued with specific R&D programs on different technologies: hybrid pixels, CMOS MAPS and pixel sensors developed with vertical integration technology. The latest results on the various pixel options for the SuperB SVT will be presented.
Physics and high background conditions set very challenging requirements on readout speed, material budget and resolution for the innermost layer of the SuperB Silicon Vertex Tracker operated at the ...full luminosity. Monolithic Active Pixel Sensors (MAPS) are very appealing in this application since the thin sensitive region allows grinding the substrate to tens of microns. Deep N-Well MAPS, developed in the ST 130nm CMOS technology, achieved in-pixel sparsification and fast time stamping. Further improvements are being explored with an intense R&D program, including both vertical integration and 2D MAPS with the INMAPS quadruple well. We present the results of the characterization with IR laser, radioactive sources and beam of several chips produced with the 3D (Chartered/Tezzaron) process. We have also studied prototypes exploiting the features of the quadruple well and the high resistivity epitaxial layer of the INMAPS 180nm process. Promising results from an irradiation campaign with neutrons on small matrices and other test-structures, as well as the response of the sensors to high energy charged tracks are presented.
Diamond detectors’ response to intense high-energy electron pulses Bassanese, S.; Bosisio, L.; Cautero, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
February 2023, 2023-02-00, Letnik:
1047
Journal Article
Recenzirano
Diamond crystals are characterised by wide band gap and high binding energy, making them suitable as solid-state particle detectors, beam-loss monitors and dosimeters in high-radiation environments, ...such as particle colliders. In order to use them as radiation and beam-loss monitors, our diamond detectors are calibrated in steady conditions with different radiation sources, comparing the measurement results with dedicated simulations. However large radiation bursts may lead to a non-linear signal response. For this purpose we studied their transient response to collimated, sub-picosecond, ∼1 GeV electron beam bunches, with a bunch charge of tens of pC, provided by the FERMI electron linac in Trieste. In these experimental conditions the ionisation generates large charge carrier density in the diamond bulk. This high charge causes a transient modification of diamond electrical properties, which affects the output signal shape. The observed signal evolution in the time domain shows fair agreement with a two-step numerical simulation of the diamond time response to these intense high-energy pulses.
We designed, constructed and have been operating a system based on single-crystal synthetic diamond sensors, to monitor the beam losses at the interaction region of the SuperKEKB asymmetric-energy ...electron–positron collider. The system records the radiation dose-rates in positions close to the inner detectors of the Belle II experiment, and protects both the detector and accelerator components against destructive beam losses, by participating in the beam-abort system. It also provides complementary information for the dedicated studies of beam-related backgrounds. We describe the performance of the system during the commissioning of the accelerator and during the first physics data taking.
The superB silicon vertex tracker Rizzo, G.; Avanzini, C.; Batignani, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The SuperB asymmetric
e
+
–
e
-
collider has been designed to deliver a luminosity greater than
10
36
cm
-
2
s
-
1
with moderate beam currents. Comparing to current B-Factories, the reduced center of ...mass boost of the SuperB machine requires improved vertex resolution to allow precision measurements sensitive to New Physics. We present the conceptual design of the silicon vertex tracker (SVT) for the SuperB detector with the present status of the R&D on the different options under study for its innermost Layer0.
In September 2008 the SLIM5 collaboration submitted a low material budget silicon demonstrator to test with 12
GeV/
c protons, at the PS-T9 test-beam at CERN. Two different detectors were placed as ...DUTs inside a high-resolution and fast-readout beam telescope. The first DUT was a high resistivity double sided silicon detector, with short strips (“striplets”) and with reduced thickness, at
45
∘
angle to the detector's edge, readout by the data-driven FSSR2 chip. The other one was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology, providing digital sparsified readout. In the following, I present the striplets and also the beam telescope characteristics, with some details about the frontend readout (based on the FSSR2 chip) and some preliminary results of the data-analysis.
Deep n-well MAPS in a 130 nm CMOS technology: Beam test results Lusiani, A; Manghisoni, M; Re, V ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
We report on recent beam test results for the APSEL4D chip, a new deep n-well MAPS prototype with a full in-pixel signal processing chain obtained by exploiting the triple well option of the CMOS ...inline image process. The APSEL4D chip consists of a 4096 pixel matrix (32 rows and 128 columns) with inline image pixel cell area, with custom readout architecture capable of performing data sparsification at pixel level. APSEL4D has been characterized in terms of charge collection efficiency and intrinsic spatial resolution under different conditions of discriminator threshold settings using a 12 GeV/c proton beam in the T9 area of the CERN PS. We observe a maximum hit efficiency of 92% and we estimate an intrinsic resolution of about inline image. The data driven approach of the tracking detector readout chips has been successfully used to demonstrate the possibility to build a Level 1 trigger system based on associative memories. The analysis of the beam test data is critically reviewed along with the characterization of the device under test.
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