Spin-polarization of an ultrarelativistic electron beam head-on colliding with an ultraintense laser pulse is investigated in the quantum radiation-reaction regime. We develop a Monte-Carlo method to model electron radiative spin effects in arbitrary electromagnetic fields by employing spin-resolved radiation probabilities in the local constant field approximation. Due to spin-dependent radiation reaction, the applied elliptically polarized laser pulse polarizes the initially unpolarized electron beam and splits it along the propagation direction into two oppositely transversely polarized parts with a splitting angle of about tens of milliradians. Thus, a dense electron beam with above 70% polarization can be generated in tens of femtoseconds. The proposed method demonstrates a way for relativistic electron beam polarization with currently achievable laser facilities.Introduction. Spin-polarized electron beams have been extensively employed to investigate matter properties, atomic and molecular structures [1][2][3]. In high-energy physics, relativistic polarized electron beams can be used to probe the nuclear structure [4,5], generate polarized photons [6,7] and positrons [6,8], study parity violation in Møller scattering [9] and new physics beyond the Standard Model [10]. There are many methods to generate polarized electron beams at low energies [1]. However, for relativistic electron beams, there are mainly two methods [11]. In the first method mostly used in the Stanford Linear Accelerator, the polarized electrons are first extracted from a photocathode (illuminated by a circularly polarized light) [12,13] and then, accelerated by the linear accelerator (alternatively one may use polarized electrons from spin filters [14] or beam splitters [15], with subsequent laser wakefield acceleration [16]). The second method is a direct way of polarization of a relativistic electron beam in a storage ring via radiative polarization (Sokolov-Ternov effect) [17][18][19][20][21][22][23][24]. The polarization time of the latter due to the synchrotron radiation is rather slow (typically from minutes to hours), since the magnetic fields of a synchrotron are too weak (in the order of 1 Tesla). The electrons are polarized transversely due to Sokolov-Ternov effect. As mostly longitudinal polarization is interesting in high-energy physics, spin rotation systems are applied [25]. Moreover, for creating polarized positron beams (also applicable for electrons) Compton scattering or Bremsstrahlung of circularly polarized lasers and successive pair creation are commonly used [26][27][28][29][30]. The polarization of relativistic electrons can be detected by Compton scattering [31], Møller scattering [32], or other methods.

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Generation of circularly-polarized (CP) and linearly-polarized (LP) γ-rays via the single-shot interaction of an ultraintense laser pulse with a spin-polarized counterpropagating ultrarelativistic electron beam has been investigated in nonlinear Compton scattering in the quantum radiation-dominated regime. For the process simulation a Monte Carlo method is developed which employs the electron-spin-resolved probabilities for polarized photon emissions. We show efficient ways for the transfer of the electron polarization to the high-energy photon polarization. In particular, multi-GeV CP (LP) γ-rays with polarization of up to about 90% (95%) can be generated by a longitudinally (transversely) spin-polarized electron beam, with a photon flux at a single shot meeting the requirements of recent proposals for the vacuum birefringence measurement in ultrastrong laser fields. Such high-energy, high-brilliance, high-polarization γ-rays are also beneficial for other applications in high-energy physics, nuclear physics, and laboratory astrophysics.

The dependence of polarization switching on thermal histories has been investigated for K1+-modified lead zirconate titanate (PZT) ceramics by Sawyer–Tower polarization methods. It was found that double-loop-like polarization characteristics in the aged condition could be reversed to normal single loop polarization characteristics by quenching specimens from above the ferroelectric phase transition temperature. However, the P–E curves reversed back to double-loop-like characteristics after reaging specimens at elevated temperatures. Excess oxygen vacancies in La3+-modified PZT were not found to result in double-loop-like polarization hysteresis, whereas excess oxygen vacancies in K1+-modified PZT did. These results provide evidence for role of K1+-oxygen vacancy complexes in polarization pinning.

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Relativistic spin-polarized positron beams are indispensable for future electron-positron colliders to test modern high-energy physics theory with high precision. However, present techniques require very large scale facilities for those experiments. We put forward a novel efficient method for generating ultrarelativistic polarized positron beams employing currently available laser fields. For this purpose the generation of polarized positrons via multiphoton Breit-Wheeler pair production and the associated spin dynamics in single-shot interaction of an ultraintense laser pulse with an ultrarelativistic electron beam is investigated in the quantum radiation-dominated regime. The pair production spin asymmetry in strong fields, significantly exceeding the asymmetry of the radiative polarization, produces locally highly polarized particles, which are split by a specifically tailored small ellipticity of the laser field into two oppositely polarized beams along the minor axis of laser polarization. In spite of radiative de-polarization, a dense positron beam with up to about 90% polarization can be generated in tens of femtoseconds. The method may eventually usher high-energy physics studies into smaller-scale laser laboratories.

Objectives: To analyze the risk factors for systemic inflammatory response syndrome (SIRS) after percutaneous nephrolithotomy (PCNL) and to quantitatively predict the probability of SIRS after PCNL. Methods: Medical records on 209 patients who underwent PCNL were retrospectively analyzed. The c 2 test, the t-test and a logistic regression model were used to identify key risk factors of SIRS after PCNL. A predictive equation was then formulated to assess the risk of SIRS according to the results from the logistic model. Subsequently, the accuracy of the equation by calculating sensitivity, specificity, overall correct percentage, and positive and negative predictive values was tested. Results: The incidence of SIRS after PCNL was 23.4%. The key risk factors for SIRS following PCNL were: the number of tracts, receipt of a blood transfusion, stone size, and presence of pyelocaliectasis. Other factors added no independent risk to the development of SIRS. The calculated values for sensitivity, specificity, overall percentage correct, positive predictive value and negative predictive value were 44.9%, 95.0%, 83.3%, 73.3%, and 84.9%, respectively. Conclusions: Number of tracts, receipt of a blood transfusion, stone size and presence of pyelocaliectasis are identified as the key risk factors for SIRS after PCNL. The predictive equation allows for an individualized and quantitative assessment of the probability of SIRS after PCNL.

Ultrasound-guided renal access for percutaneous nephrolithotomy (PCNL) is a safe, effective, and low-cost procedure commonly performed worldwide, but a technique underutilized by urologists in the United States. The purpose of this article is to familiarize the practicing urologist with methods for ultrasound guidance for percutaneous renal access. We discuss two alternative techniques for gaining renal access for PCNL under ultrasound guidance. We also describe a novel technique of using the puncture needle to reposition residual stone fragments to avoid additional tract dilation. With appropriate training, ultrasound-guided renal access for PCNL can lead to reduced radiation exposure, accurate renal access, and excellent stone-free success rates and clinical outcomes.