1,484 research outputs found
Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector
The extreme radiation dose received by vertex detectors at the Large Hadron
Collider dictates stringent requirements on their cooling systems. To be robust
against radiation damage, sensors should be maintained below -20 degree C and
at the same time, the considerable heat load generated in the readout chips and
the sensors must be removed. Evaporative CO2 cooling using microchannels etched
in a silicon plane in thermal contact with the readout chips is an attractive
option. In this paper, we present the first results of microchannel prototypes
with circulating, two-phase CO2 and compare them to simulations. We also
discuss a practical design of upgraded VELO detector for the LHCb experiment
employing this approach.Comment: 12 page
Spectral characterization of a SPDC source with a fast broadband spectrometer
Knowing the properties of the single photons produced in a Spontaneous
Parametric Down-Conversion (SPDC) source can be crucial for specific
applications and uses. In particular, the spectral properties are of key
relevance. Here, we investigate a commercial SPDC source using our fast
broadband spectrometer. Our analysis is a valid method for other SPDC sources,
as well as other single-photon generation techniques, thus providing a good
example of how to use this spectrometer design. We calibrate the spectrometer
using known lines of the argon emission spectrum. We show that the two
down-converted photons from the SPDC source have different spectral properties
depending on the pump power, and in which condition we measured spectrally
similar down-converted photons. Lastly, we were able to reconstruct and
investigate the spectral information for the pump photon
Classification of four-qubit entangled states via Machine Learning
We apply the support vector machine (SVM) algorithm to derive a set of
entanglement witnesses (EW) to identify entanglement patterns in families of
four-qubit states. The effectiveness of SVM for practical EW implementations
stems from the coarse-grained description of families of equivalent entangled
quantum states. The equivalence criteria in our work is based on the stochastic
local operations and classical communication (SLOCC) classification and the
description of the four-qubit entangled Werner states. We numerically verify
that the SVM approach provides an effective tool to address the entanglement
witness problem when the coarse-grained description of a given family state is
available. We also discuss and demonstrate the efficiency of nonlinear kernel
SVM methods as applied to four-qubit entangled state classification.Comment: 10 pages, 8 figure
Fat cosmic ray tracks in charge-coupled devices
Cosmic rays are particles from the upper atmosphere which often leave bright
spots and trails in images from telescope CCDs. We investigate so-called ``fat"
cosmic rays seen in images from Vera C. Rubin Observatory and the Subaru
Telescope. These tracks are much wider and brighter than typical cosmic ray
tracks, and therefore are more capable of obscuring data in science images. By
understanding the origins of these tracks, we can better ensure that they do
not interfere with on-sky data. We compare the properties of these tracks to
simulated and theoretical models in order to identify both the particles
causing these tracks as well as the reason for their excess spread. We propose
that the origin of these tracks is cosmic ray protons, which deposit much
greater charge in the CCDs than typical cosmic rays due to their lower
velocities. The generated charges then repel each other while drifting through
the detector, resulting in a track which is much wider than typical tracks.Comment: 13 pages, 7 figures. Accepted to JATI
Electrical Properties of Carbon Fiber Support Systems
Carbon fiber support structures have become common elements of detector
designs for high energy physics experiments. Carbon fiber has many mechanical
advantages but it is also characterized by high conductivity, particularly at
high frequency, with associated design issues. This paper discusses the
elements required for sound electrical performance of silicon detectors
employing carbon fiber support elements. Tests on carbon fiber structures are
presented indicating that carbon fiber must be regarded as a conductor for the
frequency region of 10 to 100 MHz. The general principles of grounding
configurations involving carbon fiber structures will be discussed. To
illustrate the design requirements, measurements performed with a silicon
detector on a carbon fiber support structure at small radius are presented. A
grounding scheme employing copper-kapton mesh circuits is described and shown
to provide adequate and robust detector performance.Comment: 20 pages, 11 figures, submitted to NI
Development of ultra-light pixelated ladders for an ILC vertex detector
The development of ultra-light pixelated ladders is motivated by the
requirements of the ILD vertex detector at ILC. This paper summarizes three
projects related to system integration. The PLUME project tackles the issue of
assembling double-sided ladders. The SERWIETE project deals with a more
innovative concept and consists in making single-sided unsupported ladders
embedded in an extra thin plastic enveloppe. AIDA, the last project, aims at
building a framework reproducing the experimental running conditions where sets
of ladders could be tested
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B^0_s mixing at D0 experiment
In this report, we present a report on B{sub s}{sup 0} mixing studies at the D0 experiment. New results based on use of two additional decay modes are discussed and limits are given on the B{sub s}{sup 0} mixing parameter
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