Residual-Gas-Ionization Beam Profile Monitors in RHIC

Abstract

Four ionization profile monitors (IPMs) in RHIC measure vertical and horizontal beam profiles in the two rings (yellow and blue). These work by measuring the distribution of electrons produced by beam ionization of residual gas. In 2007 a prototype of a new design was installed in the yellow ring. During the 2007-2008 run it proved to be almost completely free from backgrounds from rf coupling, electron clouds and x-rays from upstream beam loss. In 2009 four new IPMs were built based on the prototype. During the 2009 shutdown two of these IPMs were installed. This paper describes the new IPMs and shows data from the 2010 beam run. The new IPMs have been extremely important in the commissioning of the RHIC stochastic cooling system.

Absolute beam emittance measurements at RHIC using ionization profile monitors

“…The first prototype was built and tested in 1996 [1] with first measurements in RHIC in 1999 [2,3]. In 2002 two changes were made motivated by experiences with beam: shielding was added upstream of the detectors to prevent signal contributions from upstream beam losses and the electrodes were made longer to avoid electron clouds from migrating into the region of the detector [4]. In 2005 fast signal gating was added to avoid depletion of the multichannel plate (MCP) detector and better isolation of the detector from the electromagnetic fields of the beam was implemented [4].…”

“…In 2002 two changes were made motivated by experiences with beam: shielding was added upstream of the detectors to prevent signal contributions from upstream beam losses and the electrodes were made longer to avoid electron clouds from migrating into the region of the detector [4]. In 2005 fast signal gating was added to avoid depletion of the multichannel plate (MCP) detector and better isolation of the detector from the electromagnetic fields of the beam was implemented [4]. As the beam intensities increased, this latter effect was further suppressed with a new design in 2007 which placed all electronics inside a Faraday cage outside of the path of the beam's image current [5].…”

“…In 2005 fast signal gating was added to avoid depletion of the multichannel plate (MCP) detector and better isolation of the detector from the electromagnetic fields of the beam was implemented [4]. As the beam intensities increased, this latter effect was further suppressed with a new design in 2007 which placed all electronics inside a Faraday cage outside of the path of the beam's image current [5]. The prototype for this new design [5] was implemented for the Yellow Ring vertical plane (YV) in 2008.…”

“…As the beam intensities increased, this latter effect was further suppressed with a new design in 2007 which placed all electronics inside a Faraday cage outside of the path of the beam's image current [5]. The prototype for this new design [5] was implemented for the Yellow Ring vertical plane (YV) in 2008. In 2010 the new design [5] was implemented for both the Blue and Yellow Ring horizontal planes (BH, YH) and these IPMs were moved to locations where the beam sizes were larger.…”

Analysis of Vernier Scans during RHIC Run-13

“…Using measured effective beta functions (according to Equation 10 and based on the measurements listed in Table 4) , the RMS normalized emittances can be derived from the vernier scans: The IPM measurements [11] were supplied with a 10% error, the emittance measurements from the vernier scans with a 5% error. However, the errors of the IPM measurements are estimated at this point.…”