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Cesaratto, J. M.

Publications and source records attributed to Cesaratto, J. M..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

High-intensity-beam study of O 17 ( p , γ ) F 18 and thermonuclear reaction rates for O 17 + p

Hydrogen burning of the oxygen isotopes takes place in low-mass stars, asymptotic giant branch stars, and classical novae. Observations of oxygen elemental and isotopic abundances in stellar spectra or in presolar grains provide strong constraints for stellar models if reliable thermonuclear reaction rates for hydrogen burning of oxygen are available. We present the results of a new measurement of the 17 O ( p , γ ) 18 F reaction in the laboratory bombarding energy range of 170 – 530 keV. The measurement is performed with significantly higher beam intensities ( I max ≈ 2 mA) compared to previous work and by employing a sophisticated γ -ray coincidence spectrometer. We measured the cross section at much lower energies than previous in-beam experiments. Furthermore we apply a novel data-analysis method that is based on the decomposition of different contributions to the measured pulse-height spectrum. Our measured strengths of the low-energy resonances amount to ω γ pres ( 193 keV ) = ( 1.86 ± 0.13 ) × 10 - 6 eV and ω γ pres ( 518 keV ) = ( 13.70 ± 0.96 ) × 10 - 3 eV. For the direct capture S factor at zero energy, we find a value of S DC pres ( 0 ) = 4.82 ± 0.41 keV b. We also present new thermonuclear rates for the 17 O + p reactions, taking into account all consistent results from previous measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Amplifier Test

For this test, we used the existing back end configuration. For the burst type signal we used the excitation system, and for the continuous type signal we used an arbitrary function generator. The frequencies of the signal are 100, 200, 300, 400 MHz. The signals were adjusted to be approximately the same level when input into the back end chain. At the MUX out load we measure the signal with a Tektronix oscilloscope, triggering on the load signal itself, recording 1K turns (fiducial triggers). The negative (${V{_{load}^{-p}}}$) and positive (${V{_{load}^{p}}}$) peak voltages generated were recorded, from which peak to peak voltages (${V{_{load}^{pp}}}$) were computed. The input signal was attenuated by 10 dB compared to the normal operating signal used for beam excitation as a cautionary measure. One measurement was made at normal operating power. We measure the loads of two amplifiers, amp 2 and amp 4.

ACCPHY↗
DOE OSTI2012

Excitation of Intra-bunch Vertical Motion in the SPS - Implications for Feedback Control of Ecloud and TMCI Instabilities

Electron cloud (ecloud) and transverse mode coupled-bunch instabilities (TMCI) limit the bunch intensity in the CERN SPS. This paper presents experimental measurements in the SPS of single-bunch motion driven by a GHz bandwidth vertical excitation system. The final goal is to quantify the change in internal bunch dynamics as instability thresholds are approached, and quantify the frequencies of internal modes as ecloud effects become significant. Initially, we have been able to drive the beam and view its motion. We show the excitation of barycentric, head-tail and higher vertical modes at different bunch intensities. The beam motion is analyzed in the time domain, via animated presentations of the sampled vertical signals, and in the frequency domain, via spectrograms showing the modal frequencies vs. time. The demonstration of the excitation of selected internal modes is a significant step in the development of the feedback control techniques.

43 PARTICLE ACCELERATORS↗