PubMed Health⌕ Search

Biomedical subjects

S Krinsky

Publications and source records attributed to S Krinsky.

18 recordsLinked to original sources
PubMed2006

Statistical analysis of the chaotic optical field from a self-amplified spontaneous-emission free-electron laser.

We use Rice's theory of shot noise random processes to provide a statistical analysis of the evolution of the amplitude and phase of the chaotic optical field from a high-gain, self-amplified, spontaneous-emission (SASE) free-electron laser. The theoretical framework developed is compared with recent frequency-resolved optical-gating measurements of the SASE output at the LEUTL facility at Argonne National Laboratory.

Journal Article↗
PubMed2004

Model for nonlinear behavior in the self-amplified spontaneous-emission free-electron laser.

We introduce a simplified model for the saturation of a self-amplified spontaneous-emission free-electron laser. Within this model, we determine the effect of nonlinearity upon the statistical properties of the output radiation. Comparing our results with the computer simulations of Saldin, Schneidmiller, and Yurkov [The Physics of Free Electron Lasers (Springer-Verlag, Berlin, 2000)], we find that the model provides a good description of the average intensity, field correlation function, and coherence time, but underestimates the intensity fluctuation. Asymmetric spectral broadening phenomena are not included in the model.

Journal Article↗
PubMed2003

First ultraviolet high-gain harmonic-generation free-electron laser.

We report the first experimental results on a high-gain harmonic-generation (HGHG) free-electron laser (FEL) operating in the ultraviolet. An 800 nm seed from a Ti:sapphire laser has been used to produce saturated amplified radiation at the 266 nm third harmonic. The results confirm the predictions for HGHG FEL operation: stable central wavelength, narrow bandwidth, and small pulse-energy fluctuation.

Journal Article↗
PubMed2001

Characterization of a high-gain harmonic-generation free-electron laser at saturation.

We report on an experimental investigation characterizing the output of a high-gain harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A seed CO2 laser at a wavelength of 10.6 microm was used to generate amplified FEL output at 5.3 microm. Measurement of the frequency spectrum, pulse duration, and correlation length of the 5.3 microm output verified that the light is longitudinally coherent. Investigation of the electron energy distribution and output harmonic energies provides evidence for saturated HGHG FEL operation.

Journal Article↗
PubMed2000

High-gain harmonic-generation free-electron laser

A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded free-electron laser to produce amplified, longitudinally coherent, Fourier transform-limited output at a harmonic of the seed laser. A seed carbon dioxide laser at a wavelength of 10.6 micrometers produced saturated, amplified free-electron laser output at the second-harmonic wavelength, 5.3 micrometers. The experiment verifies the theoretical foundation for the technique and prepares the way for the application of this technique in the vacuum ultraviolet region of the spectrum, with the ultimate goal of extending the approach to provide an intense, highly coherent source of hard x-rays.

Journal Article↗
PubMed1998

Initial results from an in-vacuum undulator in the NSLS X-ray ring.

A short-period in-vacuum undulator for the NSLS X-ray Ring has been developed in a collaboration between SPring-8 and the NSLS, and has achieved its project design goals during commissioning studies. The device is called IVUN (in-vacuum undulator) and employs magnet arrays (31 periods, with an 11 mm period) developed at SPring-8, while the requisite vacuum chamber and mechanical systems were developed at the NSLS. At a magnet gap of 3.3 mm, IVUN produces 4.6 keV radiation in the fundamental, with useful photon fluxes in both the second and third harmonics. The magnet gap is adjustable between 2 and 10 mm. A brief overview of IVUN is presented, together with initial commissioning results: the dependence of electron-beam lifetime and bremsstrahlung on magnet gap, and the output radiation spectrum.

Journal Article↗
PubMed1986

Thyroid ectopia in a congenital hypothyroid infant.

An infant girl was referred for thyroid screening. The T4 value was 5.0 micrograms/dl (normal 5.0-13.0 micrograms/dl), and the thyroid-stimulating hormone-radioimmunoassay value was greater than 60.0 microIU/ml (normal 0-10.0 microIU/ml). Imaging failed to demonstrate thyroid tissue in the normal anatomic position in the neck. A focal collection of activity was seen, however, on a scan corresponding to the position of the base of the tongue. The finding is consistent with the diagnosis of a lingual (undescended) thyroid.

Choristoma↗
PubMed1983

Gastric emptying and obesity.

Abnormal gastric emptying in the obese has been previously suggested. To explore this concept, we studied a group of 77 subjects composed of 46 obese and 31 age-, sex-, and race-matched nonobese individuals. All of the subjects underwent quantitative fluid/solid gastric emptying assays utilizing a dual radionuclide technique. For the solid phase, obese subjects were found to have a more rapid emptying rate than nonobese subjects (p less than 0.05). Obese men were found to empty much more rapidly than their nonobese counterparts (p less than 0.01). In 4 obese subjects whose weight loss was to within 10% of their ideal weight, repeat gastric emptying studies revealed no change in liquid or solid emptying rates. The elimination patterns of gastric emptying for liquids and solids were identical to those described previously, and did not differ between the obese and nonobese groups. No correlation between body surface area and gastric emptying rates of solids or liquids could be found. The rate of solid gastric emptying in the obese subjects is abnormally rapid. No clear-cut explanation for this finding yet exists.

Adult↗
PubMed1982

The use of a single gamma camera in radionuclide assessment of gastric emptying.

The assessment of gastric emptying rates by radionuclide labeled test meals has been developing over the past decade. Some investigators have advocated the use of two gamma counters positioned anteriorly and posteriorly to the stomach to attain accurate measurements. Theoretical considerations and phantom studies presented herein demonstrate that a single gamma counter may be used with acceptable accuracy. Application of the technique described will allow for the clinical assessment of gastric emptying in virtually any nuclear medicine department.

Gastric Emptying↗