The Recycler Electron Cooler

Abstract

The Recycler Electron cooler was the first (and so far, the only) cooler working at a relativistic energy (γ = 9.5). It was successfully developed in 1995-2004 and was in operation at Fermilab in 2005-2011, providing cooling of antiprotons in the Recycler ring. This paper describes the cooler, difficulties in achieving the required electron beam parameters and the ways to overcome them, cooling measurements, and details of operation.

Fermilab 4.3 MeV electron cooler

“…Hence, to attain an electron dc current of 0.1-0.5 A, a recirculation scheme was employed, in which the electron beam that has interacted with the antiprotons is decelerated to 3.5 keV and accepted into the collector, located in the high-voltage terminal of the Pelletron. The typical relative beam current loss in the system was 2×10 -5 [9]. Note that for commissioning purposes, the electron gun was capable of operating in a pulse mode (typically, 2 s at 1 Hz).…”

“…Note that if the variations of the Coulomb logarithm in the integrand of Eq. (1) can be neglected, C L can be removed from the integrand and the instantaneous cooling rates of an antiproton beam with a Gaussian velocity distribution can be expressed with elementary functions [9].…”

“…With a detailed description of improvements and measurements given in Ref. [9], here we would like only to highlight several important milestones in the evolution of the electron beam angles:…”

Numerical Tests on Zonal Disintegration within Rockmass Around Deep Tunnel under Dynamic Disturbance

“…Thereinto, the zonal disintegration phenomena [2] is in the excavation of deep rock roadway or cavern, in its sides and in front of work of the surrounding rock produced successive alternate ruptured zone and unruptured zone phenomenon. This phenomenon have found in many foreign deep mines [3][4]. These deep problem is no longer the linear superposition factors science system which we are familiar with the factors, but nonlinear science system, caused great concern of the international rock mechanics engineering field experts and scholars, become the great interest in this field research hot spot in recent years [5].…”