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Lecture on Targets

Lecture on Targets. A. Introduction scattering exp ., gas target , storage ring B. Basics on Vacuum , Gas Flow etc pumps , molecular flow & tubes , T- shaped storage cell C. Integration of Gas Targets into Storage Rings requirements on beam optics and vacuum systems

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Lecture on Targets

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  1. Lecture on Targets A. Introduction scatteringexp., gas target, storage ring B. Basics on Vacuum, Gas Flow etc pumps, molecularflow & tubes, T-shapedstoragecell C. Integration of Gas Targets into Storage Rings requirements on beam opticsandvacuumsystems D. Summary E. Steffens "Lecture on Targets"

  2. Lecture on Targets – additional material Traditional Nuclear Physics Scattering experiment Beam from (Tandem) accelerator directed on a thin foil target, e.g. thin Carbon foil covered with a layer containing the target atoms under study. Versatile method to study Energy Levels and Structure of Nuclei throughout the periodic system! Today, the technology of targets is a very diverse field, ranging from high-power production targets for secondary beams (e.g. pions, anti-protons) to radioactive targets and gas targets (e.g. spin polarized). Our focus is on “Gas Targets for Storage Rings”. E. Steffens "Lecture on Targets"

  3. Gas Target in a Storage Ring The basic principle of storage ring experiment is shown schematically. In order to minimize Coulomb losses at the target, it is placed at the center of a low-beta section, where the acceptance angle is high. Electron Cooling (or Stochastic Cooling) may be used in order to compensate for the energy loss and beam blow-up by the target. In this way, storage times of several hours can be accomplished. E. Steffens "Lecture on Targets"

  4. T-shaped Storage Cell in a Storage Ring Sketch ofthe FILTEX-Target (Rathmann, Steffens, Zapfe et al., 1992). The FILTEX experimentdemonstrated „Spin Filtering“ of an ion beam forthefirst time, i.e. polarizing a circulating beam byspin-dependentattenuation on an internaltarget(spin-filteringofneutronshadbeendemonstrated in the 1960‘s by Shapiro et al in Dubna). E. Steffens "Lecture on Targets"

  5. T-shaped Storage Cell in a Storage Ring View into FILTEX scattering chamber (under vacuum!) • center: T-shaped target cell • right: cell support and panel of cryo pump • background: permanent sextupole magnet for focusing a polarized hydrogen beam into the cell E. Steffens "Lecture on Targets"

  6. FILTEX Experiment at the TSR Heidelberg E. Steffens "Lecture on Targets"

  7. Polarized H&D Gas Target for HERMES HERMES experiment: Deep-inelastic electron scattering at 27.5 GeV Located in the electron ring of the HERA ep-collider (1992 – 2007) at DESY, Hamburg Top view: HERA ep-collider Protons 920 GeV Electrons 27.5 GeV E. Steffens "Lecture on Targets"

  8. HERMES Target at HERA view along beam direction E. Steffens "Lecture on Targets"

  9. Design of the HERMES Target Cell Celloptimizedforoperation in an electronstorage ring Conductingsurfacewith smooth variationofcrosssectionavoidsexcitationofwakefields! System of W collimatorsforprotectionagainst beam and SR Cooled via coolingrailsbycold He gas to 60-100K 75mm Al wallswithDrifilmcoating E. Steffens "Lecture on Targets"

  10. Cooler Synchrotron COSY (FZJ) p, d with momenta up to 3.7 GeV/c • internal experiments – • with circulating beam • external experiments – • with extracted beam E. Steffens "Lecture on Targets"

  11. ANKE Target Storage cell (top, bottom) and ABS (right) with target chamber and central dipole (blue). E. Steffens "Lecture on Targets"

  12. Overview PAX Target E. Steffens "Lecture on Targets"

  13. PAX Target Cell walls made up by very thin teflon foils. Movable to provide large cell opening during beam injection! Top right: b-function in the target region (blue: horizontal, red: vertical) Right: Arrangement of quadru-pole lenses (yellow) and special low-bquadrupoles (blue) E. Steffens "Lecture on Targets"

  14. Conclusions • Targets are part of a (fixed target) Scattering Experiment. There is a large variety of different techniques for making the optimum target for a particular experiment. • Modern scattering experiments are often performed in Storage Rings with phase space cooling. They require windowless Gas Targets in order to limit energy loss and beam blow-up. • Scattering of spin-polarized particles is studied at COSY (FZJ) in order to learn about the spin-dependence of the strong force. For these experiments, spin-polarized beams and targets are required. • Spin-polarized gas targets for storage rings are based on the T-shaped storage cell, into which a beam of polarized atoms is injected. In this way, a triangular density of the polarized gas (e.g. hydrogen or deuterium) along the straight beam tube can be produced, resulting in a much higher areal density as compared with the atomic beam itself. • For more details see Review Article! E. Steffens "Lecture on Targets"

  15. Der Spin, die Wünschelrute in den Händen des Physikers frei nach E. W. Otten (Mainz) File of target review paper (48 p.) available E. Steffens "Lecture on Targets"

  16. Thank You! E. Steffens "Lecture on Targets"

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