Higher order spin resonances in a 2.1-GeV/c polarized proton beam.

Spin resonances can depolarize or spin flip a polarized beam. We studied 1st and higher order spin resonances with stored 2.1 GeV/c vertically polarized protons. The 1st order vertical (ν(y)) resonance caused almost full spin flip, while some higher order ν(y) resonances caused partial depolarization. The 1st order horizontal (ν(x)) resonance caused almost full depolarization, while some higher order ν(x) resonances again caused partial depolarization. Moreover, a 2nd order ν(x) resonance is about as strong as some 3rd order ν(x) resonances, while some 3rd order ν(y) resonances are much stronger than a 2nd order ν(y) resonance. One thought that ν(y) spin resonances are far stronger than ν(x), and that lower order resonances are stronger than higher order; the data do not support this.

Narrow spin resonance width and spin flip with an rf-bunched deuteron beam.

We used an rf solenoid to study the widths of rf spin resonances with both bunched and unbunched beams of 1.85 GeV/c polarized deuterons stored in the COSY synchrotron. With the unbunched beam at different fixed rf-solenoid frequencies, we observed only partial depolarization near the resonance. However, the bunched beam's polarization was almost fully flipped; moreover, its resonance was much narrower. We then used Chao's recent equations to explain this behavior and to calculate the polarization's dependence on various rf-solenoid and beam parameters. Our data and calculations indicate that a bunched deuteron beam's polarization can behave as if the beam has zero momentum spread.

Experimental test of a new technique to overcome spin-depolarizing resonances.

We recently tested a new spin resonance crossing technique, Kondratenko Crossing (KC), by sweeping an rf-solenoid's frequency through an rf-induced spin resonance with both the KC and traditional fast crossing (FC) patterns. Using both rf bunched and unbunched 1.85 GeV/c polarized deuterons stored in COSY, we varied the parameters of both crossing patterns. Compared to FC with the same crossing speed, KC reduced the depolarization by measured factors of 4.7 +/- 0.3 and 19_{-5};{+12} for unbunched and bunched beams, respectively. This clearly showed the large potential benefit of Kondratenko Crossing over fast crossing.

Experimental verification of predicted beam-polarization oscillations near a spin resonance.

The Chao matrix formalism allows analytic calculations of a beam's polarization behavior inside a spin resonance. We recently tested its prediction of polarization oscillations occurring in a stored beam of polarized particles near a spin resonance. Using a 1.85 GeV/c polarized deuteron beam stored in the COoler SYnchrotron, we swept a new rf solenoid's frequency rather rapidly through 400 Hz during 100 ms, while varying the distance between the sweep's end frequency and the central frequency of an rf-induced spin resonance. Our measurements of the deuteron's polarization near and inside the resonance agree with the Chao formalism's predicted oscillations.

[Case report: mast cell leukosis in a neonatal calf]. / Fallbericht: Mastzellenleukose bei einem neugeborenen Kalb.

Multicentric mast cell tumours in a newborn Fleckvieh-calf are described. The calf showed clearly pronounced lesions over the whole body. The lesions were multiple raised, cutaneous, greyisch-red and partially ulcerated. It died three hours after birth. Pathohistological examinations resulted in multiple mast cell tumours within the dermis. In addition multifocal to diffuse mast cell aggregations were observed in several internal organs including the lymph nodes and the bone marrow. No evidence for the presence of bovine leukemia virus was found by both investigating a lymph node homogenate of the calf and a blood sample of the mother cow. In this paper the pathomorphology of this rare disease is described, a possible cause is discussed and a short review of the available literature is presented.

Achieving 99.9% proton spin-flip efficiency at higher energy with a small RF dipole.

We recently used a new ferrite rf dipole to study spin flipping of a 2.1 GeV/c vertically polarized proton beam stored in the COSY Cooler Synchrotron in Jülich, Germany. We swept the rf dipole's frequency through an rf-induced spin resonance to flip the beam's polarization direction. After determining the resonance's frequency, we varied the frequency range, frequency ramp time, and number of flips. At the rf dipole's maximum strength and optimum frequency range and ramp time, we measured a spin-flip efficiency of 99.92+/-0.04%. This result, along with a similar 0.49 GeV/c IUCF result, indicates that, due to the Lorentz invariance of an rf dipole's transverse integralBdl and the weak energy dependence of its spin-resonance strength, an only 35% stronger rf dipole should allow efficient spin flipping in the 100 GeV BNL RHIC Collider or even the 7 TeV CERN Large Hadron Collider.

First spin flipping of a stored spin-1 polarized beam.

We recently studied spin flipping of a 270 MeV vertically polarized deuteron beam stored in the Indiana University Cyclotron Facility Cooler Ring. We adiabatically swept an rf solenoid's frequency through an rf-induced spin resonance and observed its effect on the deuterons' vector and tensor polarizations. After optimizing the resonance crossing rate and maximizing the solenoid's voltage, we measured a vector spin-flip efficiency of 94.2%+/-0.3%. We also found striking behavior of the spin-1 tensor polarization.

99.6% spin-flip efficiency in the presence of a strong Siberian snake.

We recently studied the spin-flipping efficiency of an rf-dipole magnet using a 120-MeV horizontally polarized proton beam stored in the Indiana University Cyclotron Facility Cooler Ring, which contained a nearly full Siberian snake. We flipped the spin by ramping the rf dipole's frequency through an rf-induced depolarizing resonance. By adiabatically turning on the rf dipole, we minimized the beam loss. After optimizing the frequency ramp parameters, we used 100 multiple spin flips to measure a spin-flip efficiency of 99.63+/-0.05%. This result indicates that spin flipping should be possible in very-high-energy polarized storage rings, where Siberian snakes are certainly needed and only dipole rf-flipper magnets are practical.

[Myocutaneous island flaps as a new principle in plastic and reconstructive head and neck surgery]. / Myokutane Insellappen als neues Prinzip der plastisch-rekonstruktiven Kopf-Hals-Chirurgie.

After a brief introductory presentation of typical regional flaps for surgical repair of cervicofacial defects, the author describes the principle, the advantages, and the disadvantages of myocutaneous island flaps. The central position and the great value of the acromiopectoral myocutaneous island flap (pectoralis major-flap) for reconstructive practice are emphasised. This flap allows the total one-stage repair of the hypopharynx and cervical oesophagus.

[Variability of island flaps for closure of cervicofacial defects]. / Die Variabilität der Insellappenplastik zum Verschluss zervikofazialer Defekte.

The author reports on the possibilities offered by plastic surgery for the closure of cervicofacial defects using different island flaps. Indications, advantages and disadvantages are described. The great value of myocutaneous island flaps from the acromiopectoral region, based on the thoracoacromial vessels, is pointed out.

[Reconstruction possibilities in extensive face and neck defects]. / Rekonstruktionsmöglich-keiten grosser Gesichts-und Halsdefekte.

In this article the author reports about typical methods of reconstructive surgery for the closure of large facial and cervical defects. In particular, he describes the rotation and transposition flaps from the forehead, the cheek, the breast, the cervical and nuchal region, and their combination. Several clinical cases are demonstrated.

[Application possibilities of symmetrical and asymmetrical serial Z plasty for correction of facial and neck scars (author's transl)]. / Anwendungsmöglichkeiten der symmetrischen und asymmetrischen Serien-Z-Plastik für die Korrektur von Narben des Gesichtes und Halses.

After review of the principles of the simple and multiple Z-plasty the authors demonstrate clinical cases of primary facial wound closure and correction of large cervical scars.

Primary one-stage repair of large lateral defects of the nose.

We report our procedure for a primary one-stage repair of a large lateral defect of the nose.

[Improved correction of saddle nose deformity by means of axial wire-stabilization (author's transl)]. / Verbesserte Sattelnasenkorrektur durch axiale Drahtstabilisierung

After having made some introductory comments on the problems of saddle nose correction, the author reports about an own improved operating technique characterized by axial wire-stabilization of the implanted cartilage and demonstrates accessible results.

[Modern methods of partial nasal reconstruction (author's transl)]. / Moderne Methoden des partiellen Nasenersatzes

On the basis of selected examples on the possibilities of partial reconstruction of the nose with special regard to cosmetically advantageous reconstructive methods is reported. Our preference is given to the frontotemporal flap following Schmid, which is performed in several operation stages and varied in dependence upon the position and largeness of nasal defects. However, for older patients the nasolabial flap is recommended, because it is an one-stage operation technique.