67 research outputs found
First emittance measurement of the beam-driven plasma wakefield accelerated electron beam
Next-generation plasma-based accelerators can push electron beams to GeV
energies within centimetre distances. The plasma, excited by a driver pulse, is
indeed able to sustain huge electric fields that can efficiently accelerate a
trailing witness bunch, which was experimentally demonstrated on multiple
occasions. Thus, the main focus of the current research is being shifted
towards achieving a high quality of the beam after the plasma acceleration. In
this letter we present beam-driven plasma wakefield acceleration experiment,
where initially preformed high-quality witness beam was accelerated inside the
plasma and characterized. In this experiment the witness beam quality after the
acceleration was maintained on high level, with final energy spread and
resulting normalized transverse emittance after the acceleration.
In this article, for the first time to our knowledge, the emittance of the PWFA
beam was directly measured
First emittance measurement of the beam-driven plasma wakefield accelerated electron beam
Next-generation plasma-based accelerators can push electron beams to GeV energies within centimeter
distances. The plasma, excited by a driver pulse, is indeed able to sustain huge electric fields that can
efficiently accelerate a trailing witness bunch, which was experimentally demonstrated on multiple
occasions. Thus, the main focus of the current research is being shifted towards achieving a high quality of
the beam after the plasma acceleration. In this paper we present a beam-driven plasma wakefield
acceleration experiment, where initially preformed high-quality witness beam was accelerated inside the
plasma and characterized. In this experiment the witness beam quality after the acceleration was maintained
on high level, with 0.2% final energy spread and 3.8 ÎĽm resulting normalized transverse emittance after the
acceleration. In this article, for the first time to our knowledge, the emittance of the plasma wakefield
accelerated beam was directly measure
Energy spread minimization in a beam-driven plasma wakefield accelerator
Next-generation plasma-based accelerators can push electron bunches to
gigaelectronvolt energies within centimetre distances. The plasma, excited by a
driver pulse, generates large electric fields that can efficiently accelerate a
trailing witness bunch making possible the realization of laboratory-scale
applications ranging from high-energy colliders to ultra-bright light sources.
So far several experiments have demonstrated a significant acceleration but the
resulting beam quality, especially the energy spread, is still far from state
of the art conventional accelerators. Here we show the results of a beam-driven
plasma acceleration experiment where we used an electron bunch as a driver
followed by an ultra-short witness. The experiment demonstrates, for the first
time, an innovative method to achieve an ultra-low energy spread of the
accelerated witness of about 0.1%. This is an order of magnitude smaller than
what has been obtained so far. The result can lead to a major breakthrough
toward the optimization of the plasma acceleration process and its
implementation in forthcoming compact machines for user-oriented applications
Hypoinsulinemia Regulates Amphetamine-Induced Reverse Transport of Dopamine
The behavioral effects of psychomotor stimulants such as amphetamine (AMPH) arise from their ability to elicit increases in extracellular dopamine (DA). These AMPH-induced increases are achieved by DA transporter (DAT)-mediated transmitter efflux. Recently, we have shown that AMPH self-administration is reduced in rats that have been depleted of insulin with the diabetogenic agent streptozotocin (STZ). In vitro studies suggest that hypoinsulinemia may regulate the actions of AMPH by inhibiting the insulin downstream effectors phosphotidylinositol 3-kinase (PI3K) and protein kinase B (PKB, or Akt), which we have previously shown are able to fine-tune DAT cell-surface expression. Here, we demonstrate that striatal Akt function, as well as DAT cell-surface expression, are significantly reduced by STZ. In addition, our data show that the release of DA, determined by high-speed chronoamperometry (HSCA) in the striatum, in response to AMPH, is severely impaired in these insulin-deficient rats. Importantly, selective inhibition of PI3K with LY294002 within the striatum results in a profound reduction in the subsequent potential for AMPH to evoke DA efflux. Consistent with our biochemical and in vivo electrochemical data, findings from functional magnetic resonance imaging experiments reveal that the ability of AMPH to elicit positive blood oxygen level–dependent signal changes in the striatum is significantly blunted in STZ-treated rats. Finally, local infusion of insulin into the striatum of STZ-treated animals significantly recovers the ability of AMPH to stimulate DA release as measured by high-speed chronoamperometry. The present studies establish that PI3K signaling regulates the neurochemical actions of AMPH-like psychomotor stimulants. These data suggest that insulin signaling pathways may represent a novel mechanism for regulating DA transmission, one which may be targeted for the treatment of AMPH abuse and potentially other dopaminergic disorders
Self-amplified spontaneous emission for a single pass free-electron laser
SPARC (acronym of "Sorgente Pulsata ed Amplificata di Radiazione Coerente", i.e. Pulsed and Amplified Source of Coherent Radiation) is a single pass free-electron laser designed to obtain high gain amplification at a radiation wavelength of 500 nm. Self-amplified spontaneous emission has been observed driving the amplifier with the high-brightness beam of the SPARC linac. We report measurements of energy, spectra, and exponential gain. Experimental results are compared with simulations from several numerical codes
TESTICULAR-TUMORS IN CHILDHOOD - A NATIONAL REPORT
The Authors report preliminary data of an Italian multicentric, retrospective study of primary testicular tumors (PTT) in childhood involving 20 Italian department of pediatric surgery. Forty cases of PTT were observed during a 10-year period (1977-1987
- …