7. Biological Effectiveness of 12 C and 20 Ne Ions with Very High LET

Knowledge of radiobiological effects of heavy ions at the cellular and molecular level is of fundamental importance in the field of radiation therapy (for example C ions) and space radiation biology (for example Ne ions). One of the issues that require deeper investigations is a determination of RBE values for a wide range of LET, for all relevant doses, for many cell types and various kinds of radiations During recent years, the biological effectiveness of heavy ions has been widely investigated with the aim to identify physical characteristics relevant to biological actions. These investigations are pertinent to the use of heavy ions in radiosurgery and radiotherapy. What has not been investigated so thoroughly is the biological effectiveness of heavy ions at low energies and very high LET values. The LET, which is equal to the stopping power of heavy particles, increases sharply at the end of the particle's path, forming a so-called Bragg peak. The shape of the Bragg peak depends on the particle type. Because overlying beams with different energies and components of primary and secondary particles are used in radiotherapy, the knowledge of RBE values of very high LET radiation need to be well characterized. An experimental set-up designed for such investigations was constructed at the isochronic cyclotron in Heavy Ion Laboratory. A more detailed description of the set-up can be found in Ref. CHO-K1 cells have been used as a suitable biological system for our studies. The cell line is characterized by genetic stability, the ability to form colonies, a relatively rapid growth rate with a cell cycle of 12-14 hours. For exposure to ions the cells were seeded in specially designed Petri dishes, which were filled with medium, sealed by a parafilm cover and placed in a vertical sample holder mounted in an x-y-z table that was connected to a special stepping motor. The irradiated sample moved under the beam according to a planned route. Movement was initiated when the number of counts detected by the 20 o particle detector reached the preset value. When all fields have been exposed the sample holder returned to the start position. Stored information enabled to evaluate the beam stability and intensity. The whole set-up was surveyed by a digital camera. The total time of exposure per dish was between 1-5 min. depending on the dose and beam intensity. The dose rates were changed from 0.05 Gy/min. to 1 Gy/min depending on the dose. Cell survival was estimated according to standard procedure

Over 50 years of operation of the „Lech” accelerator at the Institute of Nuclear Research

Warszawski, elektrostatyczny akcelerator typu Van de Graaffa „Lech” był urządzeniem całkowicie zbudowanym w kraju. Akcelerator rozpoczął pracę w 1961 r. w Instytucie Badań Jądrowych (IBJ) w Warszawie. Konstrukcja akceleratora rozpoczęła się w 1953 r. w Instytucie Fizyki Doświadczalnej Uniwersytetu Warszawskiego. Po wielu ulepszeniach i modyfikacjach akcelerator posiadał następujące parametry: energia cząstek naładowanych od 0,1 do 3,2 MeV, stabilność energii ok. 1 keV, natężenie prądu do 50 μA, przyspieszane cząstki: protony, deuterony, jony 3He i 4He. Akcelerator był głównie używany do badań podstawowych z dziedziny fizyki jądrowej i prac aplikacyjnych stosujących metody fizyki jądrowej w innych dziedzinach fizyki i technologii.The Warsaw pressurised accelerator „Lech” of the Van de Graaff type was a completely home-made machine. It began operation in 1961 at the Institute of Nuclear Research. Construction of the accelerator was begun in 1953 by the Institute of Experimental Physics of Warsaw University. After several improvements and modifications the accelerator had the following parameters: energy from 0.1 to 3.2 MeV, energy stability about 1 keV, ion current up to 50 μA, accelerated particles protons, deuterons, 3He and 4He. The accelerator was mainly used for basic research in nuclear physics and for application of nuclear research methods in other field of physics and technology

On the analysis of the beam energy stabilization in the Van de Graaff accelerator « Lech »

In the Van de Graaff accelerator LECH the deviation of the beam energy from the desired value is detected by the standard analysing system consisting of the 90° bending magnet followed by a pair of slits. The amplified error signal from that slits is used to correct the high voltage at the terminal. Corrections of the fast component of the voltage instability are made via the corona-triode and for the slow component via adjustment of the belt charging current. In order to determine the maximum gain factors providing the stable operating conditions we have adopted a definite transfer function for the aforementioned two loop stabilizer. Next we have applied this function to the analysis of the stability of the feedback system. Although the calculation was made for parameters of the accelerator LECH, the same method is easily applicable to other Van de Graaff accelerators

On the analysis of the beam energy stabilization in the Van de Graaff accelerator « Lech »

In the Van de Graaff accelerator LECH the deviation of the beam energy from the desired value is detected by the standard analysing system consisting of the 90° bending magnet followed by a pair of slits. The amplified error signal from that slits is used to correct the high voltage at the terminal. Corrections of the fast component of the voltage instability are made via the corona-triode and for the slow component via adjustment of the belt charging current. In order to determine the maximum gain factors providing the stable operating conditions we have adopted a definite transfer function for the aforementioned two loop stabilizer. Next we have applied this function to the analysis of the stability of the feedback system. Although the calculation was made for parameters of the accelerator LECH, the same method is easily applicable to other Van de Graaff accelerators.La fluctuation d'énergie du faisceau de l'accélérateur Van de Graaff LECH est détectée par un système d'analyse standard consistant en un aimant de 90° suivi d'une paire de fentes. Le signal d'erreur venant des fentes est utilisé pour corriger la haute tension au terminal. La correction des composantes rapides est faite par l'intermédiaire de la triode - corona tandis que pour les composantes lentes on ajuste le courant de charge sur la courroie. En vue de déterminer le gain maximum compatible avec une opération stable nous avons adopté une fonction de transfert bien définie pour stabiliser les 2 boucles mentionnées ci-dessus. Ensuite nous avons appliqué cette fonction à l'analyse de la stabilité du système de courte réaction. Bien que le calcul ait été fait avec les paramètres de l'accélérateur LECH, la même méthode est facilement applicable à d'autres accélérateurs Van de Graaff

Analysis and Modeling of Domain Registration Process

The paper presents analysis of the domain name reservation process for the polish .pl domain. Two models of various time scale are constructed and finally combined to build long range high resolution model. The results of prediction are verified using real data

Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors

Solid State Nuclear Track Detectors of the CR-39/PM-355 type were irradiated with protons with energies in the range from 0.2 to 8.5 MeV. Their intensities and energies were controlled by a Si surface barrier detector located in an accelerator scattering chamber. The ranges of protons with energies of 6–7 MeV were comparable to the thickness of the PM-355 track detectors. Latent tracks in the polymeric detectors were chemically etched under standard conditions to develop the tracks. Standard optical microscope and scanning electron microscopy techniques were used for surface morphology characterization

Charged projectile spectrometry using solid-state nuclear track detector of the PM-355 type

To use effectively any radiation detector in high-temperature plasma experiments, it must have a lot of benefits and fulfill a number of requirements. The most important are: a high energy resolution, linearity over a wide range of recorded particle energy, high detection efficiency for these particles, a long lifetime and resistance to harsh conditions existing in plasma experiments and so on. Solid-state nuclear track detectors have been used in our laboratory in plasma experiments for many years, but recently we have made an attempt to use these detectors in spectroscopic measurements performed on some plasma facilities. This paper presents a method that we used to elaborate etched track diameters to evaluate the incident projectile energy magnitude. The method is based on the data obtained from a semiautomatic track scanning system that selects tracks according to two parameters, track diameter and its mean gray level