RHIC Magnets for JLEIC - PowerPoint Presentation

RHIC Magnets for JLEIC Yuhong Zhang May 11, 2018

Motivation We were asked recently by the lab management to explore W hether the RHIC magnets can be used to build the JLEIC ion collider ring without any constraint (dimensions and fit to site, e tc.)

Basic Information about RHIC Magnets Magnetic length m 9.45 Physical length m 9.7 Magnetic field T 0.4 – 3.46 (3.78) Bending radius m 243 Bending angle deg 2.23 Mechanical sagitta mm 48.5 Good field width mm 66 Ramp rate T/s 0.042 Temperature K 4.6 FODO cell length m 29.62 Packing factor 0.638 Proton energy GeV 29 – 250 (275)

JLEIC Proton Ring with RHIC Magnets Electron spin rotators and CCB in arc are not considered/included RHIC JLEIC by RHIC Magnets JLEIC baseline Dipole bending radius m 24324317713390Max. proton energyGeV275275200151102100Figure-8 angledeg1301151007777.4Arc radiusm381381277209141Arc lengthM1197206114281019633823Straight lengthm240x6355354350355292Conferencem383348323564273719752230Footprint: length 12202443187115051189Footprint: length1220762555417282

Deep Tunnel 5 R. Rimmer 2.25 times p 275 GeV

Small Apertures for Cooled Beam RHIC proton beam has no cooling  emittance is large (~20 µm 95%)  Average beam size 4 mm JLEIC ion beam is cooled, beam size at injection is < 1.6 mm JLEIC requirement of physical aperture could be a factor of 2 smaller than RHIC With a same aperture, magnet bending radius can be reduced substantially, to give more room for sagitta  243 m  139 m design orbit(0=243 m)00  d L 0 L d 0 (9.45 m, bent w/ 4.85 cm sagitta ) new orbit   Good field

JLEIC Proton Ring with RHIC Magnets RHIC JLEIC by RHIC Magnets JLEIC baseline Dipole bending radius m 243 24317713390Max. proton energyGeV275275200151102100Figure-8 angledeg1301151007777.4Arc radiusm381381277209141Arc lengthM1197206114281019633823Straight lengthm240x6355354350355292Conferencem383348323564273719752230ratio2.21.61.2~1Footprint: length 12202443187115051189Footprint: length 1220 762 555 417 282

Deep Tunnel Site-Filler 8 1.5 times P: ~200 GeV R. Rimmer

Cut-open Tunnel 9 1.2 times P: ~150 GeV

DESY Experience: Straighten the HEAR SC Magnet Cold Mass HERA SC magnets: 8.8 m, curved dipole. vacuum chamber 55 mm For ALPS (Any Light Particle Search) project: effective aperture is only 35 mm using HERA SC magnets To increase aperture, the magnet cold mass is straightened using mechanical force Idea: bend the RHIC dipole cold mass to gain more aperture, thus the bending radius can be reduced RHIC magnet can reach up to 4.6 T (33% more) HERA MagnetRHIC MagnetA. Hutton

Summary The “direct” use of RHIC SC magnets for the JLEIC ion collider requires a very large footprint, its circumference is about 4.8 km, 2.2 times of the present JLEIC baseline and also large than the RHIC circumference. This can only be realized by a deep tunnel using a tunneling machine Taking advantage of a pre-cooled JLEIC beam (thus requiring smaller physical aperture), the RHIC SC magnets can be used creatively with a smaller footprint To reach 200 GeV, the ring circumference is about 3.6 km, 1.6 times of the JLEIC baseline, and similar than the RHIC tunnel, could be a site filler with deep tunnel To reach 150 GeV, the ring circumference is about 2.7 km, 1.2 times of the JLEIC baseline, it could be a site filler with a normal depth tunnel done by a cut-and-cover method To reach 100 GeV, the ring circumference is similar to the present JLEIC baseline An new idea of physically bending the RHIC SC magnet cold mass was discussed for enlarging the aperture while strongly bending the ion beams