I. Sugai

Hybrid-type long-lived carbon stripper foils

Abstract A new method for the preparation of hybrid-type long-lived carbon stripper foils was developed. The new procedure is based on a modification of our controlled dc arc-discharge method. The carbon foils are of the multilayer type and the layers are composed of carbon particles emitted from the electrodes in the ac arc-discharge and from the cathode in the dc arc-discharge. With this simple and powerful method long lived carbon stripper foils can be prepared with higher reliability and reproducibility than with the previous procedure.

A new method for making long-lived carbon foils for heavy ion beam strippers

Abstract New methods for preparing long-lived carbon foils of approximately 10 μg/cm 2 in thickness for use as strippers in heavy ion linear accelerators have been developed. The carbon foils were made by ion beam sputtering and carbon arc-discharge techniques. Parting agents of KCl and NiCl 2 were used. Carbon was deposited onto glass slides heated to approximately 180°C. Lifetimes of the carbon foils prepared by ion beam sputtering were determined to be 5 to 55 h when irradiated with 3.0 MeV, 1 μA, Ne + ion beams. A stripper-foil changer system with a large foil capacity (more than 360 foils) was designed, fabricated, and successfully operated. In this paper, comparisons between carbon foil preparation processes and foil lifetimes are made, and a description of the foil changer system is included in the appendix.

A new technique for preparation of targets of powdered materials

Abstract We have made various targets of powdered materials for nuclear experiments by developing a centrifugal precipitation method, which is particularly useful in the cases of: (a) metals with high melting point and low vapour pressure, (b) oxides or carbonates which are difficult to be handled by the usual vacuum evaporation technique and (c) some enriched isotopes which are generally very minute in quantity (less than ∼10 mg). The powdered samples were suspended in liquid paraffin with an ultrasonic vibrator, and then centrifugally precipitated on a thin backing film of Mylar or aluminium. Uniformity in the thickness of the targets obtained in this way was measured with an α-ray thickness gauge and was known to be satisfactory. Inspection for any impurities contained in the materials used or contaminated during the preparation process was carried out by measuring the scattered protons from the targets. No significant impurity was detected larger than 10 −4 mg/cm 2 .

Hyperfine structure of the metastable p̄He+ atomcule revealed by a laser-induced (n, l) = (37, 35) → (38, 34) transition

Abstract A precise scan of the previously discovered laser-induced transition ( n, l ) = (37, 35) → (38, 34) in pHe + revealed a doublet structure with a separation of Δ ν HF = 1.70 ± 0.05 GHz. This new type of “hyperfine” splitting is ascribed to the interaction of the antiproton orbital angular momentum and the electron spin.

Charge state dependent energy loss of high velocity carbon ions in the charge state non-equilibrium region

Abstract Energy losses of high velocity bare H-like and He-like carbon ions passing through thin carbon foils were measured in the charge state non-equilibrium region. The mean energy losses for each charge state increased proportionally to the foil thickness and a clear charge state dependence was observed.

Charge state dependent energy loss of high velocity oxygen ions in the charge state non-equilibrium region

Mean energy losses of high velocity bare H-like, He-like and Li-like O ions in thin carbon foils were measured in the charge state non-equilibrium region and a clear charge state dependence was observed. The screening effect of bound projectile electrons on energy losses are deduced and compared with theoretical predictions.

Microscopic structure of flexible long-lived carbon stripper foils

Abstract We have developed flexible long-lived carbon stripper foils of about 10 μ/cm2 in thickness by a controlled dc carbon arc-discharge method. The foils are not only mechanically strong, but also long-lived under bombardment with a 3.2 MeV Ne+ ion beam of 1 μA in intensity. The mean lifetime is around 12 h. The key point in producing long-lived foils is to control the amount of carbon particles coming from the cathode by controlling the cathode spot temperature.

An application of a new type deposition method to nuclear target preparation

Abstract We have developed a new deposition method, which is based on the vibrational motion of microparticles in the electrostatic field between parallel electrodes. This method is straight forward and does not require any complicated mechanism. It has been found that this deposition technique is useful for the preparation of foils, in both the backed and unbacked condition. The first test results are reported.

Development of thick, long-lived carbon stripper foils for PSR of LANL

Abstract Thick carbon stripper foils (multi-layer thickness ≈ 200 μg/cm 2 ) have been developed for use with 800 MeV, H + ion beam in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. Foils were prepared by means of the modified controlled ACDC arc discharge method (mCADAD). The lifetime measurements of the foils made by different methods were performed using an 800 MeV proton beam of up to 85 μA in the PSR, and a 3.2 MeV Ne + ion beam of 3 μA at Tokyo Institute of Technology. The foils made by the mCADAD method showed very long lifetimes, as compared to other foils tested, for both 800 MeV p and 3.2 MeV Ne + beam bombardments.

Charge-changing contribution to energy loss of 32 MeV 3He+ in the charge state non-equilibrium region☆

Abstract Energy losses of 32 MeV 3 He ions by carbon foils were measured in the charge state non-equilibrium region. The mean energy losses exhibited an abrupt change as a functiion of the foil thickness around 40–50 μg/cm 2 . This behavior is quantitatively explained by considering the contribution from charge-changing collisions.