ABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
The phase velocity of the wakefield of a laser wakefield accelerator can, theoretically, be manipulated by shaping the longitudinal plasma density profile, thus controlling the parameters of the generated electron beam. We present an experimental method where using a series of shaped longitudinal plasma density profiles we increased the mean electron peak energy more than 50%, from 175 ± 1 MeV to 262 ± 10 MeV and the maximum peak energy from 182 MeV to 363 MeV. The divergence follows closely the change of mean energy and decreases from 58.9 ± 0.45 mrad to 12.6 ± 1.2 mrad along the horizontal axis and from 35 ± 0.3 mrad to 8.3 ± 0.69 mrad along the vertical axis. Particle-in-cell simulations show that a ramp in a plasma density profile can affect the evolution of the wakefield, thus qualitatively confirming the experimental results. The presented method can increase the electron energy for a fixed laser power and at the same time offer an energy tunable source of electrons.
ABSTRACT
We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.
ABSTRACT
PURPOSE: It is known that 50% to 68% of women with stress urinary incontinence (SUI) have sexual function impairment and avoid sexual intercourse. Reports of sexual function after SUI surgery vary, with reports of both improved function and deteriorated function. The goal of this study was to evaluate the impact of midurethral sling procedures on the sexual function of women suffering from SUI preoperatively and 36 months postoperatively. MATERIALS AND METHODS: Among 75 patients who were diagnosed with SUI and underwent the midurethral procedure, 47 patients who answered the Korean version of the Female Sexual Function Index (FSFI) Questionnaire were analyzed prospectively. The retropubic route (RPR) was used in 26 patients, whereas the transobturator route (TOR) was used in 21 patients. Fifteen patients underwent concomitant posterior colporrhaphy. The FSFI was completed before surgery and 36 months after surgery. RESULTS: The patients' mean age was 44.9 years (range, 30-59 years) and their mean parity was 2.8 (range, 0-6). There were no significant differences in the individual FSFI domain scores between before surgery and 36 months (36.8±4.57) after surgery. There were no significant differences in sexual satisfaction between the patients with concomitant posterior colporrhaphy and patients with the midurethral sling procedure only. There were no significant differences in domain score between the TOR and the RPR, but patients experienced less pain after the RPR than after the TOR. CONCLUSION: There was no significant change in overall sexual function in women undergoing the midurethral sling procedure. Attention must be paid when performing the TOR procedure because it can cause pain during intercourse.
