1,028 research outputs found
The Two-Screen Measurement Setup to Indirectly Measure Proton Beam Self-Modulation in AWAKE
The goal of the first phase of the AWAKE \cite{AWAKE1,AWAKE2} experiment at
CERN is to measure the self-modulation \cite{SMI} of the long SPS proton bunch into microbunches after traversing
of plasma with a plasma density of
. The two screen measurement setup
\cite{Turner2016} is a proton beam diagnostic that can indirectly prove the
successful development of the self-modulation of the proton beam by imaging
protons that got defocused by the transverse plasma wakefields after passing
through the plasma, at two locations downstream the end of the plasma. This
article describes the design and realization of the two screen measurement
setup integrated in the AWAKE experiment. We discuss the performance and
background response of the system based on measurements performed with an
unmodulated Gaussian SPS proton bunch during the AWAKE beam commissioning in
September and October 2016. We show that the system is fully commissioned and
adapted to eventually image the full profile of a self-modulated SPS proton
bunch in a single shot measurement during the first phase of the AWAKE
experiment.Comment: 5 pages 8 figure
Determination of railway rolling stock optimal movement modes
Purpose. To develop a methodology for simulating of an electromotive railway rolling stock in terms of power-optimal modes on a track with a given profile and a set motion graph. Methodology. We have used combined genetic algorithm to determine optimum modes of an electromotive railway rolling stock motion: a global search is performed by a genetic algorithm with a one-point crossover and roulette selection. At the final stage of the optimization procedure we have used Nelder-Mead method for the refinement of the optimum. Results. We have obtained that traction motor on a tramcar, while driving on a fixed site, has an excessive power of the cooling system. Its using only in the considered area allows to modernize the cooling system in the way of its power reducing, which in turn provides an opportunity to increase the overall efficiency of the electromotive railway rolling stock. Originality. For the first time, we have obtained the train motion equation in the program oriented form. This allows to use it for determination of electromotive railway rolling stock optimal control laws according to the Hamilton-Jacobi-Bellman method. Practical value. We have made the computer program to determine optimum modes of an electromotive railway rolling stock motion. The experimental studies of program results for the track section have confirmed the adequacy of the model, which allows to solve the traffic modes optimization problem for the tram track sections and increase the overall efficiency of the electromotive railway rolling stock.Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π° ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ Π°ΡΠΈΠ½Ρ
ΡΠΎΠ½Π½ΠΎΠ³ΠΎ ΡΡΠ³ΠΎΠ²ΠΎΠ³ΠΎ Π΄Π²ΠΈΠ³Π°ΡΠ΅Π»Ρ ΠΏΡΠΈ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π° ΠΏΠΎ ΡΠ½Π΅ΡΠ³ΠΎΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΌ ΡΠ΅ΠΆΠΈΠΌΠ°ΠΌ Π½Π° ΡΡΠ°ΡΡΠΊΠ΅ ΠΏΡΡΠΈ Ρ Π·Π°Π΄Π°Π½Π½ΡΠΌ ΠΏΡΠΎΡΠΈΠ»Π΅ΠΌ ΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π½ΡΠΌ Π³ΡΠ°ΡΠΈΠΊΠΎΠΌ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠ΅ ΡΠ΅ΠΆΠΈΠΌΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΠ°ΠΌΠΈΠ»ΡΡΠΎΠ½Π°-Π―ΠΊΠΎΠ±ΠΈ-ΠΠ΅Π»Π»ΠΌΠ°Π½Π°. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΡΠ΅ΠΆΠΈΠΌΠΎΠ² ΡΠ°Π±ΠΎΡΡ ΡΡΠ³ΠΎΠ²ΠΎΠ³ΠΎ ΠΏΡΠΈΠ²ΠΎΠ΄Π° ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΎ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΡΡ Π·Π°ΡΠ°Π½Π΅Π΅ Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π·Π°Π΄Π°ΡΠΈ ΡΡΠ»ΠΎΠ²Π½ΠΎΠΉ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ Π΅Π³ΠΎ ΡΠ΅ΠΆΠΈΠΌΠΎΠ². ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΡ
ΡΠ΅ΠΆΠΈΠΌΠΎΠ² ΡΠ°Π±ΠΎΡΡ ΡΡΠ³ΠΎΠ²ΠΎΠ³ΠΎ ΠΏΡΠΈΠ²ΠΎΠ΄Π° Π±ΡΠ»ΠΎ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΊΠΎΠΌΠ±ΠΈΠ½ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΡΡΠ»ΠΎΠ²Π½ΠΎΠΉ ΠΌΠΈΠ½ΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΡΡΠ½ΠΊΡΠΈΠΈ. ΠΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠ΅Π΄Π»Π°Π³Π°Π΅ΠΌΠΎΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠΈ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΏΠΎΠ²ΡΡΠΈΡΡ ΠΎΠ±ΡΠΈΠΉ ΠΠΠ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π°
Hypothermic organ perfusion in the 2020s: mixing the benefits of low temperatures and dynamic flow outside the body
The cold chain supply of donor organs for transplantation has been an integral part of the delivery of transplant clinical services over the past five decades. Within the technologies used for this, hypothermic machine perfusion (HMP) was a concept, which was attractive to maintain organs under optimal conditions outside the body, and many early research studies on HMP were reported. However, it took the arrival of important new concepts to ensure that HMP was logistically feasible and valuable from an organ physiology perspective within the clinical pathways. This review provides details of the current status of HMP across the range of organs transplanted in the clinic, and discusses what new areas might benefit from applying HMP in coming years. In conclusion, HMP is now being used more frequently for clinical organ preservation in a variety of settings. As new therapies such as cell or gene therapy become more common, HMP will continue to play an important facilitator role for optimising organs in the donor pathway
Field-Driven Transitions in the Dipolar Pyrochlore Antiferromagnet GdTiO
We present a mean-field theory for magnetic field driven transitions in
dipolar coupled gadolinium titanate GdTiO pyrochlore system. Low
temperature neutron scattering yields a phase that can be regarded as a 8
sublattice antiferromagnet, in which long-ranged ordered moments and
fluctuating moments coexist. Our theory gives parameter regions where such a
phase is realized, and predicts several other phases, with transitions amongst
them driven by magnetic field as well as temperature. We find several instances
of {\em local} disorder parameters describing the transitions.Comment: 4 pages, 5 figures. v2: longer version with 2 add.fig., to appear in
PR
Indirect Self-Modulation Instability Measurement Concept for the AWAKE Proton Beam
AWAKE, the Advanced Proton-Driven Plasma Wakefield Acceleration Experiment,
is a proof-of-principle R&D experiment at CERN using a 400 GeV/c proton beam
from the CERN SPS (longitudinal beam size sigma_z = 12 cm) which will be sent
into a 10 m long plasma section with a nominal density of approx. 7x10^14
atoms/cm3 (plasma wavelength lambda_p = 1.2mm). In this paper we show that by
measuring the time integrated transverse profile of the proton bunch at two
locations downstream of the AWAKE plasma, information about the occurrence of
the self-modulation instability (SMI) can be inferred. In particular we show
that measuring defocused protons with an angle of 1 mrad corresponds to having
electric fields in the order of GV/m and fully developed self-modulation of the
proton bunch. Additionally, by measuring the defocused beam edge of the
self-modulated bunch, information about the growth rate of the instability can
be extracted. If hosing instability occurs, it could be detected by measuring a
non-uniform defocused beam shape with changing radius. Using a 1 mm thick
Chromox scintillation screen for imaging of the self-modulated proton bunch, an
edge resolution of 0.6 mm and hence a SMI saturation point resolution of 1.2 m
can be achieved.Comment: 4 pages, 4 figures, EAAC conference proceeding
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