BIW2012 - List of Authors (Lumpkin, A.H.)

Paper

Title

Page

First Results from Commissioning the Real-Time Interferometer as a Bunch-Length Monitor for Sub-mm Electron Bunches

9

J.C.T. Thangaraj, A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, R.M. Thurman-Keup
Fermilab, Batavia, USA
G. Andonian, A.Y. Murokh, A.G. Ovodenko, M. Ruelas
RadiaBeam, Santa Monica, USA

Single-shot, non-invasive bunch length measurement of sub-mm electron bunches is attractive for future high inten- sity accelerators. A real-time interferometer (RTI) has been developed and commissioned for the first time to monitor the bunch length of an electron beam in an accelerator. The RTI employs spatial autocorrelation, reflective optics, and a fast response pyro-detector array to obtain a real-time autocorrelation trace of the FIR coherent radiation from an electron beam thus providing the possibility of online bunch length diagnostics. A complete RTI system has been commissioned at the A0 photoinjector facility to measure sub-mm bunches at 13 MeV using coherent transition ra- diation. Bunch length variation (FWHM) between 0.8 ps to 1.5 ps has been measured. Bunch length estimates ex- tracted from interferograms are directly compared to those from a Martin-Puplett interferometer and a streak camera. The results show that the RTI is a viable, portable and com- plementary bunch length diagnostic for sub-mm electron bunches that could be readily deployed at an advanced ac- celerator electron beam facility.

TUBP02

Imaging Techniques for Transverse Beam-Profile/Size Monitors

119

A.H. Lumpkin
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The characterization of transverse beam profile/size by imaging relativistic beams using intercepting screens based on scintillators or optical transition radiation (OTR) is a well-established technique at many accelerators. There are several considerations in choosing the conversion mechanism including beam size, charge, beam energy, beam power, pulse structure, presence of microbunching instability effects, etc. Examples will be given for the fundamental contributions to system resolution including the scintillator screen resolution (powder thickness and single crystal effects), optical depth-of-focus aspects, and the OTR polarization and point-spread-function effects. The imaging techniques can be extended to the non-intercepting arena using optical diffraction radiation (ODR). Beam-size results and proposed ODR experiments at 23 GeV will be described. In addition, new OTR imaging results on non-relativistic beams of 60-keV electrons at FNAL and 11.4 MeV/u Uranium ions at GSI, Darmstadt will be presented as time permits.

Slides TUBP02 [1.635 MB]

TUCP03

Pilot Studies on Optical Transition Radiation Imaging of Non-relativistic Ions at GSI

130

B. Walasek-Höhne, C.A. Andre, F. Becker, P. Forck, A. Reiter, M. Schwickert
GSI, Darmstadt, Germany
A.H. Lumpkin
Fermilab, Batavia, USA

For relativistic particles optical transition radiation (OTR) is a well established method of transverse profile monitoring. Within a pilot experiment the applicability of OTR even for non-relativistic heavy ions was evaluated for the first time using an uranium beam of 11.4 MeV/u (corresponding to β=0.15) of different charge states. This study aimed to find a thermally stable OTR target for highly-ionizing heavy-ions and to detect reliable transverse profiles, taking advantage of high particle charge q. The exact gating feature of an image-intensified CCD camera was used to select the prompt OTR signal versus any background sources with a longer emission time constant like e.g. blackbody radiation. To test the q-dependence of the light yield, a moveable stripping foil upstream of the target was installed to increase the mean charge. During initial tests, a stainless steel target proved superior thermal behaviour and q2 dependence was observed. Profile comparison with SEM-Grid data as well as the analysis of spectroscopic measurements will be presented.

Slides TUCP03 [6.112 MB]

Paper	Title	Page
MOBP02	First Results from Commissioning the Real-Time Interferometer as a Bunch-Length Monitor for Sub-mm Electron Bunches	9
	J.C.T. Thangaraj, A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, R.M. Thurman-Keup Fermilab, Batavia, USA G. Andonian, A.Y. Murokh, A.G. Ovodenko, M. Ruelas RadiaBeam, Santa Monica, USA
	Single-shot, non-invasive bunch length measurement of sub-mm electron bunches is attractive for future high inten- sity accelerators. A real-time interferometer (RTI) has been developed and commissioned for the first time to monitor the bunch length of an electron beam in an accelerator. The RTI employs spatial autocorrelation, reflective optics, and a fast response pyro-detector array to obtain a real-time autocorrelation trace of the FIR coherent radiation from an electron beam thus providing the possibility of online bunch length diagnostics. A complete RTI system has been commissioned at the A0 photoinjector facility to measure sub-mm bunches at 13 MeV using coherent transition ra- diation. Bunch length variation (FWHM) between 0.8 ps to 1.5 ps has been measured. Bunch length estimates ex- tracted from interferograms are directly compared to those from a Martin-Puplett interferometer and a streak camera. The results show that the RTI is a viable, portable and com- plementary bunch length diagnostic for sub-mm electron bunches that could be readily deployed at an advanced ac- celerator electron beam facility.

TUBP02	Imaging Techniques for Transverse Beam-Profile/Size Monitors	119
	A.H. Lumpkin Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The characterization of transverse beam profile/size by imaging relativistic beams using intercepting screens based on scintillators or optical transition radiation (OTR) is a well-established technique at many accelerators. There are several considerations in choosing the conversion mechanism including beam size, charge, beam energy, beam power, pulse structure, presence of microbunching instability effects, etc. Examples will be given for the fundamental contributions to system resolution including the scintillator screen resolution (powder thickness and single crystal effects), optical depth-of-focus aspects, and the OTR polarization and point-spread-function effects. The imaging techniques can be extended to the non-intercepting arena using optical diffraction radiation (ODR). Beam-size results and proposed ODR experiments at 23 GeV will be described. In addition, new OTR imaging results on non-relativistic beams of 60-keV electrons at FNAL and 11.4 MeV/u Uranium ions at GSI, Darmstadt will be presented as time permits.
	Slides TUBP02 [1.635 MB]

TUCP03	Pilot Studies on Optical Transition Radiation Imaging of Non-relativistic Ions at GSI	130
	B. Walasek-Höhne, C.A. Andre, F. Becker, P. Forck, A. Reiter, M. Schwickert GSI, Darmstadt, Germany A.H. Lumpkin Fermilab, Batavia, USA
	For relativistic particles optical transition radiation (OTR) is a well established method of transverse profile monitoring. Within a pilot experiment the applicability of OTR even for non-relativistic heavy ions was evaluated for the first time using an uranium beam of 11.4 MeV/u (corresponding to β=0.15) of different charge states. This study aimed to find a thermally stable OTR target for highly-ionizing heavy-ions and to detect reliable transverse profiles, taking advantage of high particle charge q. The exact gating feature of an image-intensified CCD camera was used to select the prompt OTR signal versus any background sources with a longer emission time constant like e.g. blackbody radiation. To test the q-dependence of the light yield, a moveable stripping foil upstream of the target was installed to increase the mean charge. During initial tests, a stainless steel target proved superior thermal behaviour and q2 dependence was observed. Profile comparison with SEM-Grid data as well as the analysis of spectroscopic measurements will be presented.
	Slides TUCP03 [6.112 MB]