Crystal deflector for highly efficient channeling extraction of a proton beam from accelerators

Abstract

The design and manufacturing details of a new crystal deflector for proton beams are reported. The technique allows one to manufacture a very short deflector along the beam direction ͑2 mm͒. Thanks to that, multiple encounters of circulating particles with the crystal are possible with a reduced probability of multiple scattering and nuclear interactions per encounter. Thus, drastic increase in efficiency for particle extraction out of the accelerator was attained ͑85%͒ on a 70 GeV proton beam. We show the characteristics of the crystal deflector and the technology behind it.

The schemes of proton extraction from IHEP accelerator using bent crystals

“…2), beneficially using the effect of anticlastic bending [33]. Some of the silicon wafers used for deflectors have undergone chemical polishing treatment in Ferrara [39]. Three different "strip"-type crystals (bent in IHEP from different silicon wafers) have demonstrated record 85% efficiency of channeling [33,39].…”

Manufacturing and characterization of bent silicon crystals for studies of coherent interactions with negatively charged particles beams

“…The key factors which lead to spread of this technology in worldwide accelerators were the increasing of channeling efficiency and the discovery of the VR effect, both achieved thanks to the advent of innovative crystal manufacturing processes [12][13][14] and geometries [15][16][17]. A high steering efficiency, both with channeling ($80%) and VR (more than 95%), was obtained with positive particles [18,19], while, comparatively, very little has been achieved concerning steering of negatively charged particle beams in bent crystals [20][21][22][23][24].…”

Studies of nanotube channeling for efficient beam scraping at accelerators

“…The halo intensity in LHC is order of 10 9 proton/s. In typical channeling tests at IHEP U-70, crystal channeled ~10 12 protons in a spill of 0.5-1 s duration [11]. One of the IHEP crystals served in the vacuum chamber of U-70 over 10 years, from 1989 to 1999, delivering beam to particle physicists, until a new crystal replaced it.…”

“…The technique of particle beam channeling by bent crystals is well established at accelerators [1] and demonstrated in the energy range spanning over six decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For instance, bent crystals are largely used for extraction of 70-GeV protons at IHEP (Protvino) [10][11][12]15,16] with efficiency reaching 85% at intensity of 10 12 particle per second, steered by silicon crystal of just 2 mm in length [11].…”

“…For instance, bent crystals are largely used for extraction of 70-GeV protons at IHEP (Protvino) [10][11][12]15,16] with efficiency reaching 85% at intensity of 10 12 particle per second, steered by silicon crystal of just 2 mm in length [11]. Following the successful experiments on crystal channeling in accelerator rings, there has been a strong interest to apply channeling technique in a TeV-range collider for beam extraction or collimation [2][3][4][7][8][9][17][18][19].…”