Double Sided Silicon Strip Detectors (DSSSD) are highly segmented detectors that are widely used in nuclear physics especially in radioactive beam experiments where, due to the low beam intensities, ...one needs to cover large solid angles with high granularity. A study of the response of DSSSDs, using 7Li and 16O beams at different energies is presented. In order to characterize the detector behavior for events corresponding to particles entering the detector in the interstrip gap both for ohmic and junction sides, signals of positive and negative polarities were acquired at the same time. Different procedures for the selection of full energy events and for the determination of the corresponding efficiencies are shown and discussed.
Gamma-ray and neutron spectra from the
18
O
+
76
Se
reaction at 15.3 MeV/u were measured with the EDEN array of liquid scintillators at the LNS. The results were compared to GEANT Hadrontherapy ...physics list simulations in order to assess the reliability of this model for the development of the NUMEN project. A good agreement with the shape of the experimental gamma-ray spectra and a reasonable agreement with the total count rates were obtained. The gamma spectra originated from the nuclear reactions were selected by time coincidence with the Superconducting Cyclotron radio-frequency reference signal. The random coincidence background rate was appropriately described only when the Faraday Cup, the material and geometry of the experimental hall and its contents were included in the simulation with sufficient detail. The information on the radiation spectra is important for the adequate development of the project of the detector arrays and electronic equipment for the advanced phase of NUMEN. Since orders of magnitude larger beam intensities are planned for this phase, the random coincidence rate is also of significant importance, particularly for the performance of the G-NUMEN gamma calorimeter array.
Double Sided Silicon Strip Detectors (DSSSDs) are segmented silicon detectors widely used for the detection of charged particles. When a charged particle hits the gap between two adjacent strips, a ...signal, different from the full energy one, can be generated, resulting in an incorrect energy information. With the purpose of studying inter-strip effects on the detector response, an experiment was performed using a proton micro-beam. The response of two DSSSDs, 75 and 998μm thick, was measured as a function of the proton impact position, beam energy and bias voltage using a low intensity proton micro-beam of about few hundred particles per second (pps). Results show that the effective width of the inter-strip region, which in turn is related to the efficiency for full energy detection, varies with both detected energy and bias voltage. The experimental results are interpreted within a simplified model.
We present preliminary data of elastic scattering and inclusive breakup cross sections for the 7Li+ 119Sn reaction, recently measured at the Laboratori Nazionali del Sud (LNS-INFN) (Catania, Italy) ...at energies around the Coulomb barrier (Elab = 21.2 and 26.5 MeV). The experimental data have been analyzed under the Optical Model and Continuum-Discretized Coupled-Channels methods.
The
40
Ca(
18
O,
18
F)
40
K single charge exchange (SCE) reaction is explored at an incident energy of 275 MeV and analyzed consistently by collecting the elastic scattering and inelastic scattering ...data under the same experimental conditions. Full quantum-mechanical SCE calculations of the direct mechanism are performed by including microscopic nuclear structure inputs and adopting either a bare optical potential or a coupled channel equivalent polarization potential (CCEP) constrained by the elastic and inelastic data. The direct SCE mechanism describes the magnitude and shape of the angular distributions rather well, thus suggesting the suppression of sequential multi-nucleon transfer processes.
The geometrical characterization of ascending thoracic aortic aneurysms in clinical practice is limited to diameter measurements. Despite growing interest in hemodynamic assessment, its relationship ...with ascending thoracic aortic aneurysm pathogenesis is poorly understood. This study examines the relationship between geometry of the ventriculo-aortic junction and blood flow patterns in ascending thoracic aortic aneurysm disease.
Thirty-three patients with ascending thoracic aortic aneurysms (exclusions: bicuspid aortic valves, connective tissue disease) underwent 4-dimensional flow magnetic resonance imaging. After image segmentation, geometrical parameters were measured, including aortic curvature, tortuosity, length, and diameter. A unique angular measurement made by the trajectory of the left ventricular outflow tract axis and the proximal aorta was also conducted. Velocity profiles were quantitatively and qualitatively analyzed. In addition, 11 patients (33%) underwent wall shear stress mapping of the ascending thoracic aortic aneurysm region using computational fluid dynamics simulation.
Greater left ventricular outflow tract aortic angles were associated with larger aortic diameters at the levels of the sinus (coefficient = 0.387, P = .014) and ascending aorta (coefficient = 0.284, P = .031). Patients with left ventricular outflow tract aortic angles greater than 60° had marked asymmetric flow acceleration on the outer curvature in the proximal aorta, ascertained from 4-dimensional flow analysis. For patients undergoing computational fluid dynamics assessment, regression analysis found that higher left ventricular outflow tract aortic angles were associated with significantly higher wall shear stress values in the outer curve of the aorta (coefficient 0.07, 95% confidence interval 0.04-0.11, P = .002): Angles greater than 50° yielded time-averaged wall shear stress values greater than 2.5 Pa, exhibiting a linear relationship.
Our findings strengthen the hypothesis of flow-mediated ascending thoracic aortic aneurysm disease progression and that left ventricular outflow tract aortic angle may be a predictor of disease severity.
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The spectroscopy of F is of interest for nuclear astrophysics and nuclear structure. In these proceedings we will focus on the astrophysical implications and on the perspectives of the use of elastic ...scattering for the investigation of reactions of astrophysical importance. In astrophysics, fluorine and the reactions producing and destroying it play a key role in constraining models of stars in different evolutionary stages, such as the asymptotic giant branch (AGB) stars, responsible of the production of about half of the elements heavier than Fe. Indeed, s-nuclei are produced and brought to the surface thanks to mixing phenomena, together with fluorine that is produced in the same region from the same neutron source. Since the last stage in fluorine nucleosynthesis is the N(α, γ) F radiative capture, the study of the N + α elastic scattering may cast light on the fluorine synthesis. Also, F states are responsible of the appearance of resonances in the O(p,α) N reaction, leading to the production of N, later burnt to F in AGB stars through α-captures. Finally, the F spectroscopy may help constraining nuclear properties of the radioactive mirror nucleus Ne, whose states play a key role in novae modeling through the F(p,α) O reaction. In this work, the N - α elastic scattering is studied using the thick target inverse kinematics approach, allowing us to span a very large fluorine excitation energy range (∼ 6 - 10 MeV). A R-matrix analysis of the measured differential cross sections was also carried out, making it possible to determine the spin-parity and widths of a number of F states, including some previously not reported in the literature.
Background The purpose of this study was to evaluate the current practice patterns and results for use of intraoperative cholangiogram (IOC) during laparoscopic cholecystectomy (LC). Methods We ...performed a retrospective review of all patients who underwent LC between January 1, 2005 and December 31, 2009. Data variables included: preoperative laboratory and radiographic studies, indication for and findings of IOC, and perioperative management of choledocholithiasis and retained common bile duct (CBD) stones. Results There were 1,308 patients who underwent LC by 23 surgeons, of whom 266 also had an IOC (20%) performed. The majority had ultrasonography performed, 242 had an abdominal compute tomography (CT) scan, and 129 patients had a hepatobiliary iminodiacetic acid (HIDA) scan. Indications for an IOC included: diagnosis of choledocholithiasis or gallstone pancreatitis ( n = 116), abnormal liver function tests ( n = 187), and a dilated CBD ≥10 mm ( n = 182). Of the 266 IOCs, 36 patients (13.5%) had a CBD stone with the majority ( n = 26; 72%) having normal preoperative imaging studies. Only 6 patients (17%) with a CBD calculi on IOC underwent successful clearance of the calculi at the time of LC. Twenty-nine of the remaining 30 patients with a retained calculus on IOC underwent postoperative endoscopic retrograde cholangiopancreatography (ERCP) with extraction of the calculi. Of the 1,042 LCs performed without an IOC, 31 patients (3%) were diagnosed with a retained stone managed successfully by ERCP. Conclusion Our data reveals that the selective use of IOC is helpful in diagnosing and clearing CBD calculi, that the use of preoperative CBD size aids in selecting patients for IOC, and that choledocholithiasis identified with IOC or after discharge can be managed successfully with ERCP.
Abnormal esophageal body motility often accompanies gastroesophageal reflux disease (GERD). Although the effect of surgery on the pressure and behavior of the lower esophageal sphincter (LES) has ...been extensively studied, it still is unclear whether a successful fundoplication improves esophageal peristalsis.
The pre- and postoperative esophageal manometries of 71 patients who underwent a successful laparoscopic fundoplication (postoperative DeMeester score < 14.7) were reviewed. The patients were grouped according to the type of fundoplication (partial vs total) and preoperative esophageal peristalsis (normal vs abnormal): group A (partial fundoplication and abnormal esophageal peristalsis; n = 16), group B (total fundoplication and normal peristalsis; n = 41), and group C (total fundoplication and abnormal peristalsis; n = 14).
The LES pressure was increased in all the groups. A significant increase in amplitude of peristalsis was noted in groups A and C. Normalization of peristalsis was achieved in 31% of the group A patients and 86% of the group C patients. No changes occurred in group B.
Laparoscopic fundoplication increased LES pressure and the strength of esophageal peristalsis in patients with abnormal preoperative esophageal motility. A total fundoplication resulted in normalization of peristalsis in the majority of patients.
Gastroesophageal reflux disease (GERD) produces a spectrum of symptoms ranging from mild to severe. While the role of the lower esophageal sphincter in the pathogenesis of GERD has been studied ...extensively, less attention has been paid to esophageal peristalsis, even though peristalsis governs esophageal acid clearance. The aim of this study was to evaluate the following in patients with GERD: (1) the nature of esophageal peristalsis and (2) the relationship between esophageal peristalsis and gastroesophageal reflux, mucosal injury, and symptoms. One thousand six consecutive patients with GERD confirmed by 24-hour pH monitoring were divided into three groups based on the character of esophageal peristalsis as shown by esophageal manometry: (1) normal peristalsis (normal amplitude, duration, and velocity of peristaltic waves); (2) ineffective esophageal motility (IEM; distal esophageal amplitude <30 mm Hg or >30% simultaneous waves); and (3) nonspecific esophageal motility disorder (NSEMD; motor dysfunction intermediate between the other two groups). Peristalsis was classified as normal in 563 patients (56%), IEM in 216 patients (21%), and NSEMD in 227 patients (23%). Patients with abnormal peristalsis had worse reflux and slower esophageal acid clearance. Heartburn, respiratory symptoms, and mucosal injury were all more severe in patients with IEM. These data show that esophageal peristalsis was severely impaired (IEM) in 21% of patients with GERD, and this group had more severe reflux, slower acid clearance, worse mucosal injury, and more frequent respiratory symptoms. We conclude that esophageal manometry and pH monitoring can be used to stage the severity of GERD, and this, in turn, should help identify those who would benefit most from surgical treatment.
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