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The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be the world’s brightest neutron source, driven by a linear accelerator (LINAC) with an average beam power of 5 MW at 2.0 GeV beam energy. The LINAC accelerates a proton beam of 62.5 mA peak current at 4% duty cycle (2.86 ms at 14 Hz). The accelerator uses a normal conducting front-end bringing the beam energy to 90 MeV, beyond that the acceleration up to 2 GeV is performed using superconducting structures. The first protons were extracted at the ESS site during the commissioning of the ion source and low energy beam transport that started earlier this year and will continue to the next stage of the commissioning up to 21 MeV early next year. This paper gives an overview of the status of the ESS accelerator and the commissioning of the ion source and the low energy beam transport.

Alternate wetting and drying (AWD) technique has been developed and evaluated on rice (Oryza sativa) systems in several countries worldwide for increasing water use efficiency and reducing negative effects of permanent flooding, like the increase in methane emissions and arsenic availability in soil. In this study, a paddy field experiment was carried out for two years to evaluate the application in Northern Italy rice area of a moderate AWD, i.e. only implemented during the vegetative phase of the crop and ponded water maintained thereafter, compared with Continuous Flooding (CF) system. The adaptability of 12 European commercial rice cultivars to AWD was investigated in terms of crop phenology, morphological traits, root production, nitrogen (N) uptake, yield, milled rice yield and microelement concentration in grains. Results showed substantial (40.7 %) water saving probably favoured by the presence of a shallow water table. In these pedoclimatic conditions, very limited effects of a mild AWD on crop status and final productivity were recorded and the commercial cultivars did not display significant different adaptabilities to the water stress. Moreover, AWD decreased arsenic (As) concentration in grain but increased grain Cadmium (Cd) being the degree of such a response dependent upon the variety, suggesting that the genotype plays an important role in this aspect of adaptation to AWD. info:eu-repo/semantics/acceptedVersion

To provide essential beam diagnostics for the spallation target and for the tuning dump of the European Spallation Source (ESS) with its high-power, low-emittance proton beam, optical imaging systems have been developed allowing remote viewing of the beam profiles, using scintillation light from coatings on the proton beam window (PBW) at the accelerator exit and the target entry window (TW), and insertable interceptive screens at the tuning dump (TD). In this paper, we present the techniques used and the main parameters in the design of the TD system, including the optical configurations modelled in the software Zemax OpticStudio (ZOS). We also present the design principles for reflective optics which can transmit high-quality images, showing the performance of the imaging systems as predicted by ZOS and by prototyping. We take account of the requirements for initial alignment and ongoing maintenance of the optical system. Studies of the radiation and thermal environments, which impact on sensitive optical components such as cameras and mirrors, are also described, as are mechanical considerations for the vacuum vessels and screen actuators. Finally, comments are made on the applicability of similar optics to diagnostic systems at other neutron sources and accelerators.

International audience; Saclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design.Key words: Beam diagnostic / Linear proton accelerators / MCP / Strip detector / Particle beam measurements

The proton linac of the European Spallation Source, under construction in Lund, Sweden, had beam commissioning of its ion source (IS) and the following low energy beam transport (LEBT) at their final locations from September 2018 to July 2019. This was first of several beam commissioning stages for the linac of ESS, towards the start of the user program in 2023. This paper presents highlights of characterizations of the IS and LEBT from the aforementioned beam commissioning period, including behavioral change of the IS against its parameters, error source identifications of the beam trajectory in the LEBT, and preliminary characterization of the LEBT output beam against solenoid strengths in LEBT.

The 5 MW proton beam to be delivered to the ESS spallation target must be tuned to its nominal value and controlled at all times. To achieve this, a suite of beam diagnostics has been proposed and is currently been designed. It is located in two plugs, the Proton Beam Window (PBW) plug and the Proton Beam Instrumentation Plug (PBIP). Here we present the design concept for the PBIP imposed by the beam physics requirements as well as by the high power target environment, i.e. material lifetime, remote handling and waste management.

Rice cultivation in Europe is restricted to a few southern European countries. In 2015, the rice-growing acreage of Italy and Spain together comprised around 75 % of a total area of around half a million hectares. The milled rice equivalents in the EU amounted to 0.4 % of the global rice production. Japonica rice varieties are dominating in Europe. Rice is planted in spring and harvested in autumn. All rice fields in Europe are irrigated. Most rice seed is drilled. In some Spanish areas, pregerminated rice is sown by air. Average yields per hectare range between 4 and 8 tons. In some regions 10 tons can easily be achieved. Monocot weeds are prevailing with wild rice, Echinochloa, Cyperus and Heteranthera species being the most frequent representatives. Hydrellia griseola, Chilo suppressalis, Eysarcoris inconspicuus and Lissorhoptrus oryzophilus have to be regarded as the most serious insect problems. Magnaporthe grisea, Cochliobolus miyabeanus and Gibberella fujikuroi are the most widespread disease-causing organisms. A wide range of chemical and biological products is registered for rice protection. For some countries, however, costs for the registration of new products are too high compared with the low acreage so that lacking product innovation becomes a major problem. The acreage of Clearfield rice is continuously growing primarily due to wild rice as an increasing problem. Water shortage is a problem in a few areas in Spain primarily. Irrigated rice provides a habitat for a great number of organisms such as migratory birds and deserves special attention as far as biodiversity is concerned. Greenhouse gas emission and heavy metal concentration in rice fields have been a problem in some areas in the past. New cultivation methods with a reduced water consumption and new rice varieties should, however, contribute to the reduction of these problems.

Sixty years of environmental modifications have led to strong and rapid effects on the abundance of vector populations., Using historical data, we highlight the consequences of anthropogenic ecosystem modifications on the abundance of mosquitoes implicated as the current most important potential malaria vector, Anopheles hyrcanus, and the most important West Nile virus (WNV) vector, Culex modestus, in the Camargue region, France. From World War II to 1971, populations of these species increased as rice cultivation expanded in the region in a political context that supported agriculture. They then fell, likely because of decreased cultivation and increased pesticide use to control a rice pest. The species increased again after 2000 with the advent of more targeted pest-management strategies, mainly the results of European regulations decisions. An intertwined influence of political context, environmental constraints, technical improvements, and social factors led to changes in mosquito abundance that had potential consequences on malaria and WNV transmission. These findings suggest that anthropogenic changes should not be underestimated in vectorborne disease recrudescence.

In a Storage Ring Free Electron Laser (SRFEL) there is a strong interdependence between the laser beam and the electron beam from which the laser is generated. The Super ACO storage ring has a second Radio Frequency (RF) cavity at the 5th harmonic of the main RF cavity. It is used to shorten the bunch length, thereby enhancing the laser gain. Employing this RF harmonic cavity instabilities are observed with a strong effect on both the laser radiation properties and the electron beam behaviour. In this paper, we first present beam characteristics of Super-ACO as influenced by the harmonic cavity, and the instabilities of the beam due to this RF cavity. Then we discuss the FEL properties in presence of the harmonic RF cavity. In general the harmonic cavity functions as intended, and it is observed that the laser suppresses the instabilities caused by the harmonic cavity in the absence of the FEL.PACS: 41.60.Cr Free-electron lasers - 05.45.-a Nonlinear dynamics and nonlinear dynamical systems - 29.20.Dh Storage rings - 41.75.Fr Electron and positron beams

The interaction between laser pulse and electron beam of a storage ring free electron laser (SRFEL) can be described in the longitudinal phase space as a function of the longitudinal detuning, which we define as the delay per pass between the laser pulse and the electron bunch. SRFEL dynamics versus detuning is studied by comparison of measurements performed at Super ACO with a numerical code. Experimental phenomena regarding detuning have been properly predicted by simulations. Quantitative agreement for pulse duration, pulse repetition frequency, laser power, etc. has been found.

The static solution of the Fokker-Planck equation, known as the Haissinski equation and governing the longitudinal evolution of an electron beam moving in a Storage-Ring which is subject to an inductive wake field, can be expressed in an analytical form, using the Lambert W-function. We show how the use of this analytical tool allows a better understanding of the validity of the numerical solutions and the distribution normalization properties.

Designing a Storage Ring Free Electron Laser or improving the performance of an existing one first requires investigation of its longitudinal dynamics. With this aim, a 1-dimensional model, including energy spread and Microwave Instability (MI) effects, has been implemented in a numerical code. The code solves the differential equations of the longitudinal complex amplitude of the intra-cavity electric field, coupled with the differential equations describing the evolution of the electron bunch energy spread and of the MI. The agreement with experimental results of the Super-ACO FEL is also discussed.

Systematic studies on the Free Electron Laser (FEL) line and micropulse have been performed on the Super-ACO storage ring FEL with a monochromator and a double-sweep streak camera under various conditions of operation (detuning, “CW” and Q-switched mode). From these data, it appears that the FEL is usually operated very close to the Fourier limit.

Single shot transverse emittance measurement is essential to assess the beam quality and performance of new generation light sources such as linac based X-ray Free Electron Lasers (FELs) or laser plasma wakefield accelerators (LPWA). To this end, we have developed a single shot transverse emittance measurement using at least 3 screens inserted in the beam at the same time, measuring the beam size at different positions in a drift space in one single shot. In this paper, we firstly present the theoretical aspects to perform the measurement. We secondly show experimental results obtained at Diamond for a 3 GeV electron beam in the transfer line from the Booster to the Storage Ring, using this thin OTR screens method. Finally, we discuss the results showing the strength of the measurement in comparison with more standard and established emittance measurement, like the quadrupole scan method. © 2011 IOP Publishing Ltd and SISSA.

In this paper we present the experience at Diamond Light Source in the design, implementation, and operation of low momentum compaction factor lattices for the generation of short x-ray pulses and coherent THz radiation. The effects of higher-order terms in the expansion of the momentum compaction factor on beam dynamics are reviewed from a theoretical point of view, and the details of both high- and low-emittance solutions at Diamond are discussed. Measurements taken to characterize the lattices under a variety of machine conditions are presented, along with the practical limitations that exist as the momentum compaction factor is made to approach zero. © 2011 American Physical Society.

Third generation synchrotron light sources are characterized by a low emittance and a low emittance coupling. Some light sources are already operating with extremely low coupling close to 0.1%. Measurement of the transverse beam size is generally used to measure the emittance and the coupling. To this end, several systems are currently used and an x-ray pinhole camera is one of them. In this paper we derive the point spread function of the x-ray pinhole camera both analytically and numerically using the Fresnel diffraction integral and taking into account the broadband spectrum of the bending magnet source, and we show that an optimized design allows the measurement of extremely small vertical beam sizes below $5\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$. The point spread function of several scintillator screens is also measured, and it shows that the contribution of the diffraction and the screen point spread functions have to be taken into account for an accurate measurement of a low coupling. Finally, we show measurements of the vertical beam sizes as small as $6\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ for our nonoptimized setup.

060701-1 Collective effects, such as the microwave instability, influence the longitudinal dynamics of an electron beam in a storage ring. In a storage ring free electron laser (FEL) they can compete with the induced beam heating and thus be treated as a further concomitant perturbing source of the beam dynamics. Bunch length and energy spread measurements, carried out at the Super-ACO storage ring, can be correctly interpreted according to a broad-band impedance model. Quantitative estimations of the relative role that is played by the microwave instability and the laser heating in shaping the beam longitudinal dynamics have been obtained by the analysis of the equilibrium laser power. It has been performed in terms of either a theoretical limit, implemented with the measured beam longitudinal characteristics, or the numerical results obtained by a macroparticle tracking code, which includes the laser pulse propagation. Such an analysis, carried out for different operating points of the Super-ACO storage ring FEL, indicates that the laser heating counteracts the microwave instability.

Magnetic susceptibility and X- and Q-band EPR studies are reported for the Fe 2+ spin transition compound (Fe( PM-PEA ) 2 (NCS) 2 ) in powder form. An exceptionally large thermal hysteresis loop, about 60 K, has been found by both techniques. The EPR studies have been carried out on compound doped with Mn 2+ (0.1‰ of Mn/Fe). An original EPR spectra simulation program has been elaborated in order to yield data on the structural modifications accompanying the spin transition. The fine structure parameters obtained by simulations in the high-spin state of Fe 2+ , D =460, E =25, and in the low-spin state of this ion, D =235, E =20 (in 10 −4 cm −1 ) confirm that the spin transition is accompanied by a crystalline phase transformation. The Mn 2+ EPR spectra in the spin transition region can be convincingly fitted by linear combinations of the spectra observed in the high-spin and low-spin states of Fe 2+ , indicating that the spin transition occurs in domains of like-spin ions.

We present experimental measurements of the coherence of an undulator synchrotron radiation source near to the diffraction limit condition. These measurements have been done following two objectives. The first one is to verify a fundamental point of the theory of synchrotron radiation. To our knowledge, since it has been re-written by Geloni et al. [1] , no experimental verification to validate the theory has been performed. Our measurement proves the theory to be valid for the case of a near diffraction limited undulator source. The other objective is to measure the coherence of the synchrotron radiation on the I05 beamline of Diamond, in front of the last focusing element of the beamline. This knowledge can be used to predict the focusing performance of the beamline by means of Fourier Optics.