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

Sub-types of nonbelieved memories reveal differential outcomes of challenges to memories

Nonbelieved memories (NBMs) highlight the independence between metamemorial judgments that contribute to the experience of remembering. Initial definitions of NBMs portrayed them as involving the withdrawal of autobiographical belief despite sustained recollection. While people rate belief for their NBMs as weaker than recollection, the average difference is too small to support the idea that belief is completely withdrawn in all cases. Furthermore, ratings vary considerably across NBMs. In two studies, we reanalyzed reports from prior studies to examine whether NBM reports reflect a single category or multiple sub-categories using cluster analytic methods. In Study 1, we identified three sub-types of NBMs. In Study 2 we incorporated the concept of belief in accuracy, and found that two of the clusters from Study 1 split into two clusters apiece. Higher ratings of recollection than belief in occurrence characterized all clusters, which were differentiated by the degree of difference between these variables. In both studies the clusters were differentiated by a number of memory characteristic ratings and by reasons reported as leading to the alteration of belief. Implications for understanding the remembering of past events and predicting the creation of NBMs are discussed

A device to characterize optical fibres

ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting (WLS) fibres (corresponding to a total length of 1,120 Km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.Comment: 17 pages 20 figeres submitted to NIM journa

Using wearable sensors to assess freezing of gait in the real world

Freezing of gait (FOG) is a debilitating symptom of Parkinson\u27s disease (PD) that remains difficult to assess. Wearable movement sensors and associated algorithms can be used to quantify FOG in laboratory settings, but the utility of such methods for real world use is unclear. We aimed to determine the suitability of our wearable sensor-based FOG assessment method for real world use by assessing its performance during in-clinic simulated real world activities. Accuracy of the sensor-based method during simulated real-world tasks was calculated using expert rated video as the gold standard. To determine feasibility for unsupervised home use, we also determined correlations between the percent of active time spent freezing (%ATSF) during unsupervised home use and in-clinic activities. Nineteen people with PD and FOG participated in this study. Results from our sensor-based method demonstrated an accuracy above 90% compared to gold-standard expert review during simulated real-world tasks. Additionally, %ATSF from our sensor-based method during unsupervised home use correlated strongly with %ATSF from our sensor-based method during in-clinic simulated real-world activities (ρ = 0.73). Accuracy values and correlation patterns suggest our method may be useful for FOG assessment in the real world

Commissioning of the electron injector for the AWAKE experiment

The advanced wakefield experiment (AWAKE) at CERN is the first proton beam-driven plasma wakefield acceleration experiment. The main goal of AWAKE RUN 1 was to demonstrate seeded self-modulation (SSM) of the proton beam and electron witness beam acceleration in the plasma wakefield. For the AWAKE experiment, a 10-meter-long Rubidium-vapor cell together with a high-power laser for ionization was used to generate the plasma. The plasma wakefield is driven by a 400 GeV/c proton beam extracted from the super proton synchrotron (SPS), which undergoes a seeded self-modulation process in the plasma. The electron witness beam used to probe the wakefields is generated from an S-band RF photo-cathode gun and then accelerated by a booster structure up to energies between 16 and 20 MeV. The first run of the AWAKE experiment revealed that the maximum energy gain after the plasma cell is 2 GeV, and the SSM mechanism of the proton beam was verified. In this paper, we will present the details of the AWAKE electron injector. A comparison of the measured electron beam parameters, such as beam size, energy, and normalized emittance, with the simulation results was performed

Investigation of the prevalence of antibodies against neurotropic polyomaviruses BK, JC and SV40 in sera from patients affected by multiple sclerosis.

Viral agents seem to be linked to multiple sclerosis (MS). This association is based on evidence of (1) early exposure to viruses and MS onset; (2) increased prevalence of MS disease in specific geographic regions; (3) likelihood of developing MS being more prevalent in high-risk areas; (4) altered immune responses to different viruses. In this study, sera from patients affected by MS and controls, represented by sera from patients with other neurologic diseases, both inflammatory and non-inflammatory, and from healthy donors, were investigated for the presence of antibodies against neurotropic polyomaviruses BKV, JCV and SV40 in their sera. Our study has indicated that the prevalence of BKV antibodies in sera from MS patients is higher than that detected in normal individuals, while levels of antibodies against BKV and JCV are lower in MS patients compared to those of normal subjects

liquid air energy storage as a polygeneration system to solve the unit commitment and economic dispatch problems in micro grids applications

Abstract Storage technologies play a crucial role in polygeneration plants that attempt to integrate power, thermal and cooling energy systems in order to maximize process efficiency and reduce operating cost. With the increasing penetration of renewable energy into the plant, storage technologies help to dampen the intermittency problem in their energy supply whilst at the same time perform peak shaving to reduce primary energy consumption, thus mitigating pollutant emission. Among the various storage technologies, Liquid Air Energy Storage (LAES) have gathered research interest due to its capability of simultaneously producing electrical and cooling power. Furthermore, unlike Electrochemical Energy Storage (EES) technologies, the LAES lifetime is not heavily dependent on its duty cycle, thus allowing for a calendar life twice or thrice that of EES. In this paper, the economic dispatch of an Eco-building in Singapore has been evaluated using a mixed-integer quadratic programming solver by comparing the adoption of EES and LAES within a capacity range of 300kWh-2000kWh. At the higher end of the capacity range, the LAES configuration results in a higher Net Present Value after 20 years and a shorter time period to obtain the Return of Investment compared to that of EES. At the lower capacity range, both technologies give similar financial returns. Analysis of the results show LAES to be a promising technology to compete with EES in the context of a polygeneration plant and further technology integration is discussed