IBIC2012 - List of Authors (Bravin, E.)

Paper

Title

Page

Design and Operation of the High Intensity Luminosity Monitors of the LHC

179

H.S. Matis, S.C. Hedges, M. Placidi, A. Ratti, W.C. Turner
LBNL, Berkeley, California, USA
E. Bravin
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: We acknowledge the US-LARP program that is sponsoring this work and NERSC, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
We have built a high-pressure ionization chamber (BRAN) for the IP1 (ATLAS) and IP5 (CMS) regions of the LHC. This chamber is designed to measure the relative bunch-by-bunch collision rate of the LHC from 10²⁸ cm^-2s⁻¹ during beam commissioning all the way up to the expected full luminosity of 10³⁴ cm^-2s⁻¹ at 7.0 TeV. These high-pressure ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. They are designed to withstand the high radiation produced by these forward collisions and are currently used in LHC operations. This paper covers the detector's design and performance in measuring both pp and PbPb collisions during LHC operation, including a comparison with the ATLAS and CMS luminosity measurements. The work also includes modeling of the detectors and the ability to predict how the detector will respond to the higher energy and intensity operation of the LHC with different operating modes involving both ions and protons.

WECA01

Theoretical and Experimental Investigation on Resolution of Optical Transition Radiation Transverse Beam Profile Monitor

A.S. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
B. Bolzon, E. Bravin, T. Lefèvre
CERN, Geneva, Switzerland
S.T. Boogert, V. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
L.J. Nevay
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Optical Transition Radiation (OTR) appearing when a charged particle crosses an interface between two media with different dielectric constants has widely been used as a tool for transverse profile measurements of charged particle beams in numerous facilities worldwide. The basic tuning methods and operation of conventional OTR monitors are well established for transverse beam sizes not smaller than 3-5 um. Since the Point Spread Function (PSF) dimension defines the resolution of the conventional monitors, for small electron beam dimensions the PSF form significantly depends on a presence of OTR tails diffraction and aberrations in the optical system. In our experiment we have managed to squeeze the electron beam such that we can practically measure PSF distribution in one direction. The revealed PSF structure is such that the visibility depends on the transverse beam size on micron scale. We developed an empirical calibration technique and successfully overcame the resolution limit of the common OTR monitor reaching sub-micron level. Here we represent the recent developments and upgrades in both setup and data analysis of a sub-micrometer electron beam profile monitor.

Slides WECA01 [2.230 MB]

Paper	Title	Page
MOPB50	Design and Operation of the High Intensity Luminosity Monitors of the LHC	179
	H.S. Matis, S.C. Hedges, M. Placidi, A. Ratti, W.C. Turner LBNL, Berkeley, California, USA E. Bravin CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: We acknowledge the US-LARP program that is sponsoring this work and NERSC, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We have built a high-pressure ionization chamber (BRAN) for the IP1 (ATLAS) and IP5 (CMS) regions of the LHC. This chamber is designed to measure the relative bunch-by-bunch collision rate of the LHC from 10²⁸ cm^-2s⁻¹ during beam commissioning all the way up to the expected full luminosity of 10³⁴ cm^-2s⁻¹ at 7.0 TeV. These high-pressure ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. They are designed to withstand the high radiation produced by these forward collisions and are currently used in LHC operations. This paper covers the detector's design and performance in measuring both pp and PbPb collisions during LHC operation, including a comparison with the ATLAS and CMS luminosity measurements. The work also includes modeling of the detectors and the ability to predict how the detector will respond to the higher energy and intensity operation of the LHC with different operating modes involving both ions and protons.

WECA01	Theoretical and Experimental Investigation on Resolution of Optical Transition Radiation Transverse Beam Profile Monitor
	A.S. Aryshev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan B. Bolzon, E. Bravin, T. Lefèvre CERN, Geneva, Switzerland S.T. Boogert, V. Karataev Royal Holloway, University of London, Surrey, United Kingdom L.J. Nevay Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Optical Transition Radiation (OTR) appearing when a charged particle crosses an interface between two media with different dielectric constants has widely been used as a tool for transverse profile measurements of charged particle beams in numerous facilities worldwide. The basic tuning methods and operation of conventional OTR monitors are well established for transverse beam sizes not smaller than 3-5 um. Since the Point Spread Function (PSF) dimension defines the resolution of the conventional monitors, for small electron beam dimensions the PSF form significantly depends on a presence of OTR tails diffraction and aberrations in the optical system. In our experiment we have managed to squeeze the electron beam such that we can practically measure PSF distribution in one direction. The revealed PSF structure is such that the visibility depends on the transverse beam size on micron scale. We developed an empirical calibration technique and successfully overcame the resolution limit of the common OTR monitor reaching sub-micron level. Here we represent the recent developments and upgrades in both setup and data analysis of a sub-micrometer electron beam profile monitor.
	Slides WECA01 [2.230 MB]