Raimund Helm

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Forty-nine patients with fifty fractures of the scaphoid were reviewed more than six months after surgical treatment using the Herbert bone screw. Twenty-nine patients (mainly those with delayed union and non-union) also had bone grafts. The mean period of follow-up was 18.3 months. In 47 patients (94%) the fracture had definitely or probably united. The(More)
We present a new conceptual and optical design for the Next Linear Collider post-linac collimation system. Energy collimation and passive protection against off-energy beams are achieved in a system with large horizontal dispersion and vertical betatron functions. Betatron collimation is performed in a relatively low-beta (FODO-like) lattice in which only(More)
The minimum p achievable at the interaction point @*> with the current design of the SLC final focus is limited to -5 mm by third order optical aberrations, most notably the Utzti and W3466 terms (using the notation of K. Brown). A new lattice is presented which effectively zeros these terms. The remaining third order terms which accrue from the interleaved(More)
Damage by late spring frost is a risk deciduous trees have to cope with in order to optimize the length of their growing season. The timing of spring phenological development plays a crucial role, not only at the species level, but also at the population and individual level, since fresh new leaves are especially vulnerable. For the pronounced late spring(More)
The final focus of the Next Linear Collider (NLC) demagnifies electron and positron beams of 250-750 GeV energy down to a transverse size of about 2.5 x 350 nm2 at the interaction point (IP). The basic layout, momentum bandwidth, vibration tolerances, wakefield effects, and the tunability of the proposed final focus design are discussed. Also a perspective(More)
AbsfTtlCt The correction of the chromaticity of low-beta insertions in the storage rings is usual1 made with sextu le lenses in the ring’s arcs. When ecreasing the beta Kp B n&ions at the insertion point GI’), this technique becomes fairly ineffective, since it fails to properly correct the higher order chromatic aberrations. Here we consider the approach(More)
  • O. Napolyt, N. Phinney, +9 authors F. Zimmerrnann
  • 1996
We discuss a possible upgrade to the Stanford Linear Collider (SLC), whose objective is to increase the SLC luminosity by at least a factor 7, to an average Z production rate of more than 35,000 per week. The centerpiece of the upgrade is the installation of a new superconducting find doublet with a field gradient of 240 T/m, which will be placed at a(More)
The SLAC electron-positron colliding-beam project SPEAR was completed and stable colliding beams were achieved in April, 1972, after a construction period of approximately 20 months. Since that time, an active experimental high-energy physics program has begun in addition to a program of continued studies of accelerator physics. This paper discusses only(More)
This paper describes the computer studies of the electromagnetic and mechanical properties of an S-band superconducting accelerator. The structure under discussion is intended for a test accelerator using a 15-cavity niobium traveling-wave resonant-ring structure operating in the 28/3 mode. Many of the parameters for this short test accelerator, such as the(More)
Ten adults were studied two to seven years after resection of a fibula for use as a free vascularised bone graft. Six had no symptoms in the donor leg, four had some aching, weakness or paraesthesia and three had definite weakness of the long toe flexors and extensors. All knees and ankles were clinically and radiologically stable, but the distal fibular(More)