IBIC2012 - List of Authors (Evtushenko, P.E.)

Paper	Title	Page
MOPA42	Measurements of Martin-Puplett Interferometer Limitations using Blackbody Source	153
	P.E. Evtushenko, J.M. Klopf JLAB, Newport News, Virginia, USA
	Frequency domain measurements with Martin-Puplett interferometer is one of a few techniques capable of bunch length measurements at the level of ~ 100 fs. As the bunch length becomes shorter, it is important to know and be able to measure the limitations of the instrument in terms of shortest measurable bunch length. In this paper we describe experiment of using blackbody source with the modified Matrin-Puplett interferometer that is routinely used for bunch length measurements at the JLab FEL, as a way to estimate the shortest, measurable with the device, bunch. The limitation comes from high frequency cut-off of the presently used wire-grid polarizer and is estimated to be 50 fs RMS. The measurements are made with the same Golay cell detector that is used for beam measurements. We demonstrate that, even though the blackbody source is many orders of magnitude less bright than the coherent transition or synchrotron radiation, it can be used for the measurements and gives a very good signal to noise ratio in a combination with lock-in detection. We also compare the measurements made in air and in vacuum to show the very strong effect of the atmospheric absorption.

MOPB80	High Dynamic Range Beam Imaging with Two Simultaneously Sampling CCDs	263
	P.E. Evtushenko, D. Douglas JLAB, Newport News, Virginia, USA
	Transverse beam profile measurement with sufficiently high dynamic range (HDR) is a key diagnostic to measure the beam halo, understand its sources and evolution. In this contribution we describe our initial experience with the HDR imaging of the electron beam at the JLab FEL. On contrary to HDR measurements made with wire scanners in counting mode, which provide only two or three 1D projections of transverse beam distribution, imaging allows to measure the distribution itself. That is especially important for non-equilibrium beams in the LINACs. The measurements were made by means of simultaneous imaging with two CCD sensors with different exposure time. Two images are combined then numerically in to one HDR image. The system works as an online tool providing HDR images at 4 Hz. An optically polished YAG:Ce crystal with the thickness of 100 um was used for the measurements. When tested with a laser beam images with the DR of about 10⁺⁵ were obtained. With the electron beam the DR was somewhat smaller due to the limitations in the time structure of the tune-up beam macro pulse.

Paper

Title

Page

Measurements of Martin-Puplett Interferometer Limitations using Blackbody Source

153

P.E. Evtushenko, J.M. Klopf
JLAB, Newport News, Virginia, USA

Frequency domain measurements with Martin-Puplett interferometer is one of a few techniques capable of bunch length measurements at the level of ~ 100 fs. As the bunch length becomes shorter, it is important to know and be able to measure the limitations of the instrument in terms of shortest measurable bunch length. In this paper we describe experiment of using blackbody source with the modified Matrin-Puplett interferometer that is routinely used for bunch length measurements at the JLab FEL, as a way to estimate the shortest, measurable with the device, bunch. The limitation comes from high frequency cut-off of the presently used wire-grid polarizer and is estimated to be 50 fs RMS. The measurements are made with the same Golay cell detector that is used for beam measurements. We demonstrate that, even though the blackbody source is many orders of magnitude less bright than the coherent transition or synchrotron radiation, it can be used for the measurements and gives a very good signal to noise ratio in a combination with lock-in detection. We also compare the measurements made in air and in vacuum to show the very strong effect of the atmospheric absorption.

MOPB80

High Dynamic Range Beam Imaging with Two Simultaneously Sampling CCDs

263

P.E. Evtushenko, D. Douglas
JLAB, Newport News, Virginia, USA

Transverse beam profile measurement with sufficiently high dynamic range (HDR) is a key diagnostic to measure the beam halo, understand its sources and evolution. In this contribution we describe our initial experience with the HDR imaging of the electron beam at the JLab FEL. On contrary to HDR measurements made with wire scanners in counting mode, which provide only two or three 1D projections of transverse beam distribution, imaging allows to measure the distribution itself. That is especially important for non-equilibrium beams in the LINACs. The measurements were made by means of simultaneous imaging with two CCD sensors with different exposure time. Two images are combined then numerically in to one HDR image. The system works as an online tool providing HDR images at 4 Hz. An optically polished YAG:Ce crystal with the thickness of 100 um was used for the measurements. When tested with a laser beam images with the DR of about 10⁺⁵ were obtained. With the electron beam the DR was somewhat smaller due to the limitations in the time structure of the tune-up beam macro pulse.