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Ongoing progress in laser and accelerator technology opens new possibilities in high-field science, notably for the study of the largely unexplored strong-field QED regime where electron-positron pairs can be created directly from light-matter or even light-vacuum interactions. Laserless strategies such as beam-beam collisions have also been proposed with the prospect of pushing strong-field quantum electrodynamics (SFQED) in the nonpertubative regime. Here we report on an original concept to probe strong-field QED by harnessing the interaction between an electron beam and a solid target. When a high-density, ultrarelativistic beam impinges onto an even denser plasma, the beam self fields are reflected at the plasma boundary. In the rest frame of the beam electrons, these fields can exceed the Schwinger field, leading to strong-field QED effects such as quantum nonlinear inverse Compton scattering and nonlinear Breit-Wheeler electron-positron pair creation. We show that such beam-plasma collisions can produce results similar to beam-beam collisions with the advantage of a much simpler experimental setup including the automatic overlap between the beam and the reflected fields. This scenario opens the way to precision studies of strong-field QED, with measurable clear signatures in terms of gamma-ray photon and pair production, and thus is a very promising milestone on the path towards laserless studies of nonperturbative SFQED.

Plasma waves generated in the wake of intense, relativistic laser1,2 or particle beams3,4 can accelerate electron bunches to gigaelectronvolt energies in centimetre-scale distances. This allows the realization of compact accelerators with emerging applications ranging from modern light sources such as the free-electron laser to energy frontier lepton colliders. In a plasma wakefield accelerator, such multi-gigavolt-per-metre wakefields can accelerate witness electron bunches that are either externally injected5,6 or captured from the background plasma7,8. Here we demonstrate optically triggered injection9–11 and acceleration of electron bunches, generated in a multi-component hydrogen and helium plasma employing a spatially aligned and synchronized laser pulse. This ‘plasma photocathode’ decouples injection from wake excitation by liberating tunnel-ionized helium electrons directly inside the plasma cavity, where these cold electrons are then rapidly boosted to relativistic velocities. The injection regime can be accessed via optical11 density down-ramp injection12–16 and is an important step towards the generation of electron beams with unprecedented low transverse emittance, high current and 6D-brightness17. This experimental path opens numerous prospects for transformative plasma wakefield accelerator applications based on ultrahigh-brightness beams. Electron bunches are generated and accelerated to relativistic velocities by tunnel ionization of neutral gas species in a plasma. This represents a step towards ultra-bright, high-emittance beams in plasma wakefield accelerators. [This summary has been amended from ‘laser-plasma’ to ‘plasma wakefield’ accelerators.]

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a congenital condition characterizing females with absence of the uterus and part of the vagina. Several genetic defects have been correlated with the presence of MRKH; however, the exact etiology is still unknown due to the complexity of the genetic pathways implicated during the embryogenetic development of the Müllerian ducts. A systematic review (SR) of the literature was conducted to investigate the genetic causes associated with MRKH syndrome and Congenital Uterine Anomalies (CUAs). This study aimed to identify the most affected chromosomal areas and genes along with their associated clinical features in order to aid clinicians in distinguishing and identifying the possible genetic cause in each patient offering better genetic counseling. We identified 76 studies describing multiple genetic defects potentially contributing to the pathogenetic mechanism of MRKH syndrome. The most reported chromosomal regions and the possible genes implicated were: 1q21.1 (RBM8A gene), 1p31-1p35 (WNT4 gene), 7p15.3 (HOXA gene), 16p11 (TBX6 gene), 17q12 (LHX1 and HNF1B genes), 22q11.21, and Xp22. Although the etiology of MRKH syndrome is complex, associated clinical features can aid in the identification of a specific genetic defect.

An electron beam experiences chromatic emittance growth in a plasma-based accelerator if it is not matched to the focusing force in the plasma wake. A ramped plasma density profile at the entrance and exit of the plasma source can control the focusing of the beam into and out of the plasma accelerator, limiting emittance growth. Here, we present a comprehensive, analytic theory to describe the transverse beam dynamics and emittance growth in a nearly arbitrary plasma ramp profile. For a given incoming beam, this theory can be used to determine the length of the ramp required to correctly focus the electron beam, the optimal location of the beam's vacuum focus, and the chromatic emittance growth in the ramp. In addition, the theory can be used to determine the effect that errors in the beam focusing and plasma profile have on the emittance of the beam. We illustrate two example ramps to demonstrate the theory: one that provides very fast focusing for beam matching, and one that is robust to errors in the plasma density profile.

An electro-optic sampling beam position monitor for installation at the SLAC National Accelerator Laboratory FACET-II facility is described. Simulations of the detector signal were performed using realistic electron beam current profiles, demonstrating that this single-shot, non-destructive, compact detector is capable of resolving the relative transverse offset and longitudinal separation of an ultra-relativistic, two-bunch electron beam to order 1 μ m and 10 fs, respectively. A design study was performed to optimize the detector’s response to the ultra-relativistic two-bunch electron beam utilized in plasma wakefield accelerator experiments. In addition, the expected sensitivity to beam tilt is studied for typical electron beams used in free electron lasers .

Simulations and theory predict that long electron and positron beams may under favorable conditions self-modulate in plasmas. We report on the progress of experiments studying the self-modulation instability in plasma wakefield experiments at FACET. The experimental results obtained so far, while not being fully conclusive, appear to be consistent with the presence of the self-modulation instability.

Plasma wakefield accelerators (PWF A) have demonstrated GeV/m scale accelerating gradients; however, current PWFAs tend to increase the particle beam's emittance (volume of the beam in transverse phase-space) as the beam propagates through the plasma. The beam's emittance can be preserved by tailoring the longitudinal density profile of the plasma to properly focus the beam into the plasma. We present optical techniques to create controlled plasma densities via laser ionization. The longitudinal plasma density profile is determined by the evolution of the intensity of a high power laser pulse as it propagates through a gas. Control of the pulse intensity is achieved using a superposition of Bessel beams created by a tandem lens setup. The width of the plasma is limited by the refraction of the laser pulse off of the ionizing gas, but we have developed several optical techniques to create wider plasmas. Our simulations show that suitable plasma filaments with lengths up to a meter and widths up to a millimeter can be generated in an argon gas using a~ 1 0 TW peak-power Ti:sa laser pulse.

Beam-driven, underdense thin plasma lenses are a compact and tunable means of providing strong focusing to relativistic electron beams. It is necessary to focus electron beams to small sizes in a beam-driven plasma wakefield accelerator to preserve the beam emittance, or volume in phase space. The thin plasma lens can be used to achieve these small beam sizes that are otherwise out of reach of conventional electromagnetic beam delivery systems. Ultrashort (~ 30 fs), low energy (~ 10 mJ) laser pulses can be used to ionize a small region of gas to generate the thin plasma lens. The interplay between the ionized gas and the focusing of the laser pulse are modeled in detail to calculate experimentally achievable 3-D plasma lens profiles, which are then used in simulations of beam focusing. Plasma lens focal lengths and minimum beam sizes achievable are estimated, considering the effects of radiation reaction in both the classical and quantum regimes.

Electron beam emittance preservation in a beam-driven, nonlinear plasma wakefield accelerator relies upon matching the beam to the plasma. This occurs when the linear focusing forces of the ion column acting on the electron beam are perfectly balanced against the emittance-driven divergence of the beam. The matching condition is satisfied when the square of the beam size equals the product of the geometric emittance and the inverse betatron wave number of the beam inside the plasma. In practice, however, the matched beam size is too small to achieve with conventional beam delivery systems operating in vacuum. Here, a passive, tapered plasma density ramp at the entrance (exit) of the plasma source is described that can focus the electron beam to (from) the necessary matched size at a rate exceeding the adiabatic plasma focusing limit without diluting the beam's emittance. A numerically derived empirical model predicts both the plasma ramp shape and parameter tolerances required for beam matching as a function of the incoming beam parameters. These results can be easily scaled for the purpose of designing sequential plasma stages in a high-energy linear collider.

An integral part of plasma wakefield acceleration (PWFA) is producing, monitoring, and controlling a plasma source. Understanding the temporal evolution of plasma parameters allows for constraints on experimental lifetime and initial conditions. Recombination factors for low temperature (kBT less than the ionization energy), singly-ionized Argon and Hydrogen plasmas (nominal PWFA plasma sources) are investigated to develop a model of plasma decay. Due to the high density of the plasma sources collisional recombination and ionization dominates radiative processes, and the problem of modelling plasma decay simplifies to finding the recombination coefficients for these plasma sources. This recombination coefficient is presented as a function of plasma temperature to determine plasma decay for a variety of initial plasma conditions. Additionally, plasma temperature is modelled from the ponderomotive force of the ionizing laser pulse. Results are utilized for designing optimal PWFA experiments.

International audience; During the past two decades of research, the ultra-relativistic beam-driven plasma wakefield accelerator (PWFA) concept has achieved many significant milestones. These include the demonstration of ultra-high gradient acceleration of electrons over meter-scale plasma accelerator structures, efficient acceleration of a narrow energy spread electron bunch at high-gradients, positron acceleration using wakes in uniform plasmas and in hollow plasma channels, and demonstrating that highly nonlinear wakes in the 'blow-out regime' have the electric field structure necessary for preserving the emittance of the accelerating bunch. A new 10 GeV electron beam facility, Facilities for Accelerator Science and Experimental Test (FACET) II, is currently under construction at SLAC National Accelerator Laboratory for the next generation of PWFA research and development. The FACET II beams will enable the simultaneous demonstration of substantial energy gain of a small emittance electron bunch while demonstrating an efficient transfer of energy from the drive to the trailing bunch. In this paper we first describe the capabilities of the FACET II facility. We then describe a series of PWFA experiments supported by numerical and particle-in-cell simulations designed to demonstrate plasma wake generation where the drive beam is nearly depleted of its energy, high efficiency acceleration of the trailing bunch while doubling its energy and ultimately, quantifying the emittance growth in a single stage of a PWFA that has optimally designed matching sections. We then briefly discuss other FACET II plasma-based experiments including in situ positron generation and acceleration, and several schemes that are promising for generating sub-micron emittance bunches that will ultimately be needed for both an early application of a PWFA and for a plasma-based future linear collider.

Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, and measured with another 20 GeV lower charge trailing positron probe bunch. The measurements are largely consistent with theory., 5 pages, 4 figures. Submitted to Physical Review Letters

To develop plasma wakefield acceleration into a compact and affordable replacement for conventional accelerators, beams of charged particles must be accelerated at high efficiency in a high electric field; here this is demonstrated for a bunch of charged electrons ‘surfing’ on a previously excited plasma wave. Particle colliders that operate at the high-energy frontier using electric fields generated by radio waves are approaching the limits of feasibility in terms of size and cost, but there are other acceleration techniques that could make less expensive and more compact devices. The plasma wakefield accelerator, in which an electron bunch is accelerated by making it 'surf' on a plasma wave excited by another electron bunch, promises an energy gain in the gigaelectron-volt regime over just a few centimetres — an energy gain that requires hundreds of metres using traditional accelerators. Previously, this technique had only been used to accelerate a very small number of electrons at a time. Now, researchers working at FACET, the Facility for Advanced Accelerator Experimental Tests at SLAC National Accelerator Laboratory, USA, have achieved acceleration of about half a billion electrons at once with an unprecedented efficiency for a plasma accelerator. This achievement could be a milestone in the development of affordable and compact accelerators for applications ranging from high energy physics to medical and industrial applications. High-efficiency acceleration of charged particle beams at high gradients of energy gain per unit length is necessary to achieve an affordable and compact high-energy collider. The plasma wakefield accelerator is one concept1,2,3 being developed for this purpose. In plasma wakefield acceleration, a charge-density wake with high accelerating fields is driven by the passage of an ultra-relativistic bunch of charged particles (the drive bunch) through a plasma4,5,6. If a second bunch of relativistic electrons (the trailing bunch) with sufficient charge follows in the wake of the drive bunch at an appropriate distance, it can be efficiently accelerated to high energy. Previous experiments using just a single 42-gigaelectronvolt drive bunch have accelerated electrons with a continuous energy spectrum and a maximum energy of up to 85 gigaelectronvolts from the tail of the same bunch in less than a metre of plasma7. However, the total charge of these accelerated electrons was insufficient to extract a substantial amount of energy from the wake. Here we report high-efficiency acceleration of a discrete trailing bunch of electrons that contains sufficient charge to extract a substantial amount of energy from the high-gradient, nonlinear plasma wakefield accelerator. Specifically, we show the acceleration of about 74 picocoulombs of charge contained in the core of the trailing bunch in an accelerating gradient of about 4.4 gigavolts per metre. These core particles gain about 1.6 gigaelectronvolts of energy per particle, with a final energy spread as low as 0.7 per cent (2.0 per cent on average), and an energy-transfer efficiency from the wake to the bunch that can exceed 30 per cent (17.7 per cent on average). This acceleration of a distinct bunch of electrons containing a substantial charge and having a small energy spread with both a high accelerating gradient and a high energy-transfer efficiency represents a milestone in the development of plasma wakefield acceleration into a compact and affordable accelerator technology.

Despite the urgent need for a TeV-class linear collider in High-Energy Physics (HEP), a clear path to buildable and affordable accelerator technologies has yet to be realized. Clearly, the identification and advancement of next generation accelerator technologies for a linear collider have been one of the main charges since the inception of the Advanced Accelerator Concepts (AAC) workshop. The fundamental requirements of linear colliders for accelerator technologies are to demonstrate high wall-plug efficiency, high beam quality preservation, high effective gradient, scalability, etc. Within the AAC community, beam-driven wakefield acceleration schemes (the central subject of Working Group 4) are always promising and attractive approaches. Since the last AAC workshop, a few high profile experiments related to beam-driven plasma wakefield acceleration have been conducted at the SLAC National Accelerator Laboratory’s FACET facility. These experiments have successfully answered questions related to obtaining...

In a plasma wakefield accelerator (PWFA), using advanced injection techniques such as the density down-ramp injection is a promising approach for generating electron beams with ultralow emittance. In this study, we describe how such a scheme could be realized using the beam from the Linac Coherent Light Source (LCLS) accelerator as a driver. Moreover, we explore the potential applications of such high-brightness e-beams in a facility like LCLS and in novel concepts for compact FELs.

Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m−1, over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources., Plasma accelerators driven by particle beams are a promising technology, but the acceleration distance and energy gain are strongly limited by head erosion in a high-ionization-potential gas. Here the authors observe up to 130% energy boost in a self-focused electron beam, with limited head erosion.

Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

Localized injection of electrons within a relativistic plasma wake can potentially produce an ultrashort, monoenergetic electron bunch. Recent experiments at the FACET facility at SLAC explored the injection of helium electrons at the helium-lithium interface of a lithium heat pipe oven and the subsequent acceleration in the beam-produced plasma wake. Electrons accelerated to over 10 GeV in 30 cm of plasma were observed as a distinct charge bunch.

We report initial results of optical probing experiments (E-224) at the FACET/SLAC user facility. These experiments are being carried out in collaboration with the ongoing e-beam driven wakefield experimental campaign (E-200) at FACET. Their aim is to optically study both the short term and long term plasma structure produced by the e-beam driver. The SLAC plasma wakefield experiments have demonstrated the highest energy gain to date [1] and continue work on further optimization. Direct visualization of the plasma wake structure would aid in the understanding of the dynamics of the beam plasma interaction and acceleration and its optimization. Currently, such understanding is derived only from simulations, which are very time consuming and rely on limited knowledge of initial conditions. We describe the optical probing geometry used in this initial run, a variation of a method previously developed in our group [6], as governed by the unique experimental challenges of the FACET beam driven experiments in t...

Performance of the x-ray free electron laser Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET) is determined by the properties of their extremely short electron bunches. Multi-GeV electron bunches in both LCLS and FACET are less than 100 fs long. Optimization of beam properties and understanding of free-electron laser operation require electron beam diagnostics with time resolution of about 10 fs. We designed, built and commissioned a set of high frequency $X$-band deflectors which can measure the beam longitudinal space charge distribution and slice energy spread to better than 10 fs resolution at full LCLS energy (14 GeV), and with 70 fs resolution at full FACET energy (20 GeV). Use of high frequency and high gradient in these devices allows them to reach unprecedented performance. We report on the physics motivation, design considerations, operational configuration, cold tests, and typical results of the $X$-band deflector systems currently in use at SLAC.

2Although there is strong theoretical support that na-ture can be described by a grand uni ed theory (GUT) [1,2], there is currently no direct experimental evidence.One of the most powerful ways to test grand uni cationis to look for proton (or bound neutron) decay. MostGUTs have an unstable proton; in the absence of anobservation, setting experimental limits on the protonlifetime can provide useful constraints on the nature ofgrand uni ed theories. Observation, on the other hand,would be tantalizing evidence of new physics beyond theStandard Model.One of the more simple but interesting candidates forgrand uni cation is SO(10), where the Standard Model’sSU(3), SU(2), and U(1) are contained within the largergauge group. The class of models based on SO(10) uni- cation generally make predictions for neutrino massesand mixing that are broadly in accord with all knownneutrino mixing data [3, 4]. The minimal supersym-metric SO(10) model with a 126 Higgs eld describedin Ref. [3] is the particular motivation for the analysispresented here. In addition to predicting neutrino massand mixing in agreement with observations, it leaves R-parity unbroken, which guarantees the existence of stabledark matter. For some region of its allowed parameterspace, this model predicts that the dominant nucleon de-cay modes will be p! ˇ

Long (L>>λ pe ) charged particle bunches traveling in dense plasmas are subject to a transverse two-stream instability, the self-modulation instability (SMI)1. This instability modulates the bunch in the radial direction with a longitudinal period approximately equal to the plasma wavelength (λ pe ∼n e 1/2). The SMI can be used to transform a long bunch into a train of short bunches that can resonantly drive wakefields to large amplitudes. An experiment known as AWAKE2 was recently approved at CERN to drive GV/m wakefields with 400GeV, ∼12cm-long proton bunches in a 10m plasma with λ pe ∼1mm. In the linear wakefield regime, the plasma response is symmetric for positively and negatively charged bunches. However, once the nonlinear regime is approached the plasma response becomes asymmetric, leading to differences that could be evidenced using the ultra-relativistic electron and positron bunches3. This asymmetry makes it more difficult to accelerate positively than negatively charged particle bunches in plasmas.

A search for the dinucleon decay $pp\ensuremath{\rightarrow}{K}^{+}{K}^{+}$ has been performed using $91.6\text{ }\text{ }\mathrm{kton}\ifmmode\cdot\else\textperiodcentered\fi{}\text{yr}$ data from Super-Kamiokande-I. This decay provides a sensitive probe of the $R$-parity-violating parameter ${{\ensuremath{\lambda}}_{112}}^{\ensuremath{'}\ensuremath{'}}$. A boosted decision tree analysis found no signal candidates in the data. The expected background was $0.28\ifmmode\pm\else\textpm\fi{}0.19$ atmospheric neutrino induced events and the estimated signal detection efficiency was $12.6%\ifmmode\pm\else\textpm\fi{}3.2%$. A lower limit of $1.7\ifmmode\times\else\texttimes\fi{}{10}^{32}\text{ }\text{ }\text{years}$ has been placed on the partial lifetime of the decay $^{16}\mathrm{O}\ensuremath{\rightarrow}^{14}\mathrm{C}{K}^{+}{K}^{+}$ at 90% C.L. A corresponding upper limit of $7.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ has been placed on the parameter ${{\ensuremath{\lambda}}_{112}}^{\ensuremath{'}\ensuremath{'}}$.

We investigate transverse effects in the plasma-wakefield acceleration experiments planned and ongoing at FACET. We use PIC simulation tools, mainly QuickPIC, to simulate the interaction of the drive electron beam and the plasma. In FACET a number of beam dynamics knobs, including dispersion and bunch length knobs, can be used to vary the beam transverse characteristics in the plasma. We present simulation results and the status of the FACET experimental searches.

For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8×1010 electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wakefield acceleration experiments. A target foil is inserted upstream of the plasma source to increase the bunch emittance through multiple scattering. Its effect on beamplasma interaction is observed with an energy spectrometer after a vertical bend magnet. Results from the first experiments show that increasing the emittance has suppressed vapor field-ionization and plasma wakefields excitation. Plans for the future are presented.

Ionization injection in a plasma wakefield accelerator was investigated experimentally using two lithium plasma sources of different lengths. The ionization of the helium gas, used to confine the lithium, injects electrons in the wake. After acceleration, these injected electrons were observed as a distinct group from the drive beam on the energy spectrometer. They typically have a charge of tens of pC, an energy spread of a few GeV, and a maximum energy of up to 30 GeV. The emittance of this group of electrons can be many times smaller than the initial emittance of the drive beam. The energy scaling for the trapped charge from one plasma length to the other is consistent with the blowout theory of the plasma wakefield.

Searches for a nucleon decay into a charged anti-lepton (e^+ or {\mu}^+) plus a light meson ({\pi}^0, {\pi}^-, {\eta}, {\rho}^0, {\rho}^-, {\omega}) were performed using the Super-Kamiokande I and II data. Twelve nucleon decay modes were searched for. The total exposure is 140.9 kiloton \cdot years, which includes a 91.7 kiloton \cdot year exposure (1489.2 live days) of Super-Kamiokande-I and a 49.2 kiloton \cdot year exposure (798.6 live days) of Super-Kamiokande-II. The number of candidate events in the data was consistent with the atmospheric neutrino background expectation. No significant evidence for a nucleon decay was observed in the data. Thus, lower limits on the nucleon partial lifetime at 90% confidence level were obtained. The limits range from 3.6 \times 10^31 to 8.2 \times 10^33 years, depending on the decay modes., Comment: 25 pages, 18 figures

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, A new Super-Kamiokande search for supernova relic neutrinos was conducted using 2853 live days of data. Sensitivity is now greatly improved compared to the 2003 Super-Kamiokande result, which placed a flux limit near many theoretical predictions. This more detailed analysis includes a variety of improvements such as increased efficiency, a lower energy threshold, and an expanded data set. New combined upper limits on supernova relic neutrino flux are between 2.8 and 3.1ν̄e cm-2 s-1 > 16 MeV total positron energy (17.3 MeV Eν), The Super-Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the United States Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the Korean Research Foundation (BK21), the National Research Foundation of Korea (NRF- 20110024009), the Japan Society for the Promotion of Science, and the National Natural Science Foundation of China (Grants No. 10875062 and No. 10911140109)

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, The results of the third phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first and second phase results. With improved detector calibrations, a full detector simulation, and improved analysis methods, the systematic uncertainty on the total neutrino flux is estimated to be ± 2.1%, which is about two thirds of the systematic uncertainty for the first phase of Super-Kamiokande. The observed 8B solar flux in the 5.0 to 20 MeV total electron energy region is 2.32 ± 0.04 (stat.) ± 0.05 (sys.) x 10^6 cm^-2sec^-1, under the assumption of pure electron-flavor content, in agreement with previous measurements. A combined oscillation analysis is carried out using SK-I, II, and III data, and the results are also combined with the results of other solar neutrino experiments. The best-fit oscillation parameters are obtained to be sin^2 {\theta}12 = 0.30+0.02-0.01(tan^2 {\theta}12 = 0.42+0.04 -0.02) and {\Delta}m2_21 = 6.2+1.1-1.9 *10^-5eV^2. Combined with KamLAND results, the best-fit oscillation parameters are found to be sin^2 {\theta}12 = 0.31±0.01 (tan^2 {\theta}12 = 0.44±0.03) and {\Delta}m2_21 = 7.6 ± 0.2 x 10^-5 eV^2. The 8B neutrino flux obtained from global solar neutrino experiments is 5.3 ± 0.2 (stat + sys) x 10^6cm^-2s^-1, while the 8B flux becomes 5.1 ± 0.1 (stat +sys ) x 10^6cm^-2s^-1 by adding KamLAND result. In a three-flavor analysis combining all solar neutrino experiments, the upper limit of sin^2 {\theta}13 is 0.060 at 95% C.L.. After combination with KamLAND results, the upper limit of sin^2 {\theta}13 is found to be 0.059 at 95% C.L., The authors gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. Super-K has been built and operated from funds provided by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. This work was partially supported by the Research Foundation of Korea (BK21 and KNRC), the Korean Ministry of Science and Technology, the National Science Foundation of China, and the Spanish Ministry of Science and Innovation (Grants No. FPA2009- 13697-C04-02 and No. Consolider-Ingenio-2010/CPAN)

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, We present a search for differences in the oscillations of antineutrinos and neutrinos in the Super-Kamiokande-I, -II, and -III atmospheric neutrino sample. Under a two-flavor disappearance model with separate mixing parameters between neutrinos and antineutrinos, we find no evidence for a difference in oscillation parameters. Best-fit antineutrino mixing is found to be at (Δm̄2,sin22θ̄)=(2.0×10−3 eV2,1.0) and is consistent with the overall Super-K measurement, We gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. The Super- Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the United States Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the Korean Research Foundation (BK21), and the Korea Research Foundation Grants (MOEHRD, Basic Research Promotion Fund), (KRF-2008-521-c00072). Some of us have been supported by the State Committee for Scientific Research in Poland (Grant No. 1757/B/H03/ 2008/35). Some collaborators have been supported by the National Natural Science Foundation of China under Grants No. 10875062 and No. 10911140109

We report the development of a proton identification method for the Super-Kamiokande detector. This new tool is applied to the search for events with a single proton track, a high purity neutral current sample of interest for sterile neutrino searches. After selection using a neural network, we observe 38 events in the combined SK-I and SK-II data corresponding to 2285.1 days of exposure, with an estimated signal to background ratio of 1.6 to 1. Proton identification was also applied to a direct search for charged-current quasi-elastic (CCQE) events, obtaining a high precision sample of fully kinematically reconstructed atmospheric neutrinos, which has not been previously reported in water Cherenkov detectors. The CCQE fraction of this sample is 55%, and its neutrino (as opposed to anti-neutrino) fraction is 91.7+/-3%. We selected 78 mu-like and 47 e-like events in the SK-I and SK-II data set. With this data, a clear zenith angle distortion of the neutrino direction itself is reported in a sub-GeV sample of muon neutrinos where the lepton angular correlation to the incoming neutrino is weak. Our fit to nu_mu->nu_tau oscillations using the neutrino L/E distribution of the CCQE sample alone yields a wide acceptance region compatible with our previous results and excludes the no-oscillation hypothesis at 3 sigma., Comment: 23 pages, 22 figures. Corrected typos, replaced some figures. Version accepted for publication in Phys. Rev. D

We have searched for proton decays via p-->e;{+}pi;{0} and p-->micro;{+}pi;{0} using data from a 91.7 kt.yr exposure of Super-Kamiokande-I and a 49.2 kt.yr exposure of Super-Kamiokande-II. No candidate events were observed with expected backgrounds induced by atmospheric neutrinos of 0.3 events for each decay mode. From these results, we set lower limits on the partial lifetime of 8.2 x 10;{33} and 6.6 x 10;{33} years at 90% confidence level for p-->e;{+}pi;{0} and p-->micro;{+}pi;{0} modes, respectively.

A first study of neutron tagging is conducted in Super--Kamiokande, a 50,000-ton water Cherenkov detector. The tagging efficiencies of thermal neutrons are evaluated in a 0.2 % GdCl$_{3}$-water solution and pure water. They are determined to be, respectively, 66.7 % for events above 3 MeV and 20 % with corresponding background probabilities of 2 $\times$ 10$^{-4}$ and 3 $\times$ 10$^{-2}$. This newly developed technique may enable water Cherenkov detectors to identify $\bar \nu_{e}$'s geological or astrophysical sources as well as those produced by commercial reactors via the delayed coincidence scheme., Comment: 17 pages, 11 figures

International audience; The Facility for Advanced Accelerator and Experimental Tests (FACET) at SLAC installed a 10-TW Ti : sapphire laser system for pre-ionized plasma wakefield acceleration experiments. High energy (500 mJ), short (50 fs) pulses of 800 nm laser light at 1 Hz are used at the FACET experimental area to produce a plasma column. The laser pulses are stretched to 250 fs before injection into a vapor cell, where the laser is focused by an axicon lens to form a plasma column that can be sustained over the desired radius and length. A 20 GeV electron bunch interacts with this preformed plasma to generate a non-linear wakefield, thus accelerating a trailing witness bunch with gradients on the order of several GV m^−1. The experimental setup and the methods for producing the pre-ionized plasma for plasma wakefield acceleration experiments performed at FACET are described.

The Astrophysical Journal 742.2 (2011): 78, reproduced by permission of the AAS, We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at Super-Kamiokande. Data sets from SKI-SKIII (3109.6days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C.L. upper limits of upmu flux induced by WIMPs of 100GeV c-2 were 6.4 × 10-15cm -2s-1 and 4.0 × 10-15cm -2s-1 for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 × 10 -39cm-2 and 2.7 × 10-40cm-2 for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.

Die medikamentose Nierensteinauflosung hat in letzter Zeit wieder an Interesse gewonnen. Im vorliegenden Versuch sollten zunachst verschiedene heute gebrauchliche Losungsmittel an Steinen gleicher chemischer Zusammensetzung gepruft und miteinander verglichen werden. Die chemische Analyse der Steine vor und nach Bespulung in vitro sollte einen Einblick in die Frage geben, ob das Verhaltnis der einzelnen chemischen Komponenten zueinander fur den Grad des Spuleffektes von ausschlaggebender Bedeutung ist und ob dabei bestimmte Gesetzmasigkeiten vorliegen. Weiterhin interessierte die Frage, welche Steinbestandteile von den einzelnen Losungsmitteln vorzugsweise angegriffen werden.