Fragment Separator FRS(H.J. Wollersheim)

FRagment Separator FRS

	Experimental site at S2 (top view) Experimental site at S2 (side view) Experimental site at S4 luminosity=primary beam intensity/s * target atoms/cm² ²⁰⁸Pb: 1.3 g/cm² --> 3.810²¹ target atoms/cm² ⁹Be:.....1.0 g/cm² --> 6.710²² target atoms/cm²

Projectile fragmentation cross sections (EPAX-calculation)
- Production cross sections for Ni-isotopes
- Production cross sections for Sn-isotopes
- Experimental cross sections from fission and fragmentation of ²³⁸U (pdf-file)
- Yields for in-flight beams (200-400 MeV/u) RIA-project
  factor (RIA-project/GSI)~10⁴ (fragmentation)
Secondary beam rates after FRS (examples)
event rate [s^-1] ≈ luminosity [s^-1cm^-2] * cross section [cm²]
- present ¹³²Sn beam intensity: 5.8*10⁴ particles/s
- max. theo. ¹³²Sn beam intensity: 8.7*10⁵ particles/s
The optimum thickness of the production target is limited by the loss of fragments due to secondary reactions

Production cross sections for Sn-isotopes

FRS-separator
Bρ-ΔE-Bρ separation for different degrader thicknesses
Separation of fission fragments at different energies (¹⁹⁰W, d/R=0.5)
Beam attenuation: Operation domain of the Bρ-ΔE-Bρ separation
- fragments are lost in the degrader (etc) due to nuclear reactions
- Beam attenuation = 1 - nuclear reaction rate
- Beam attenuation in plastic
  more details for thick target experiments
  total reaction cross section s_reac= p*R²_int [fm²]
  nuclear interaction radius R_int=C₁+C₂+4.49-(C₁+C₂)/6.35 [fm]
  nuclear radius for Fermi distribution C_i=R_i*(1-R_i^-2) [fm]
  nuclear radius for sharp surface R_i=1.28*A_i^1/3-0.76+0.8*A_i^-1/3 [fm]

209-Bi (1GeV/u) without and with Al-target (4g/cm2)

Highly-charged ions at relativistic energies
Highly-charged ions at relativistic energies: 950MeV/u versus 160MeV/u

Charge state population versus beam energy (H.Weick)

Publications:
The GSI projectile fragment separator (FRS): a proposal for the SIS-ESR experimental programme
H. Geissel et al.
The GSI projectile fragment separator (FRS): a versatile magnetic system for relativistic heavy ions
H. Geissel et al. NIM B70, 286 (1992)
Einfluss der Umladung beim Abbremsen von Schwerionen im Energiebereich (100-1000) MeV/u
H. Weick, PhD thesis
Rare ISotopes INvestigation at GSI (RISING) using gamma-ray spectroscopy at relativistic energies
H.J. Wollersheim et al. NIM A537, 637 (2005)

last update: 7.3..2006 Hans-Juergen Wollersheim HJW