Total Track Length Research Articles

Influence of temperature on track registration in olivine

Track etch rate and total etchable track length have been compared for Xe ion tracks registered in olivine crystals, at two different temperatures (160K and 293K). A small registration temperature effect has been found. It appears to vary with the crystallographic orientation of the tracks, beeing nearly inexistent in some cases. Because of its small amplitude, this effect should not pose any serious problem for the study of ultraheavy cosmic ray tracks in meteorites.

Static Blocking at Railyards: Sorting Implications and Track Requirements

In this paper, various strategies for minimizing the amount of switching done at a classification yard are examined. We investigate how the allocation of blocks (the sorting classes recognized at the yard) to classification tracks affects switching work. Given are the sorting classes, as well as the schedule and block makeup of the departing trains. Only static strategies are considered—strategies where every block has been assigned permanently to a classification track. Simple formulas are given for the minimum number of tracks needed to implement a strategy, and for the amount of switching work given a number of tracks. The total track length is also examined. The results are significantly influenced by the number of blocks recognized by the yard; given this number, the results are nearly independent of the train departure schedule, the number of departing trains, and the number of blocks of individual trains. This feature simplifies the study of larger problems (e.g., dynamic blocking strategies) and, most importantly, makes train formation and scheduling an easier job at every yard.

Track kinetics of volume tracks in crystals

The extraterrestrial crystals provide us valuable exposed samples to study Ultra Heavy (UH) cosmic rays. Beside UH cosmic ray abundances, these studies can provide information regarding cosmic ray source history. The observed low abundances of actinides in HEAO-3 and ARIEL-VI UH cosmic ray experiments, have increased the importance of these studies. The total etchable track length is used for track identification in crystals. However lack of direct calibration to UH nuclei and proper kinetics for volume tracks are the major disadvantages of such studies. Fortunately, in the recent past, these crystals are calibrated to accelerated Uranium beam. In this paper, we describe track kinetics for volume tracks on the basis of track etch rate data for Uranium tracks. We have used the simple approach of single etchant passage to reveal the volume tracks and the variation of VETL is studied using track profiles from computer. The optimum conditions and possible charge resolution are considered from this analysis.

Study of tracks of heavy ions in quartz glass

Samples of quartz glass detector have been irradiated vertically by 129Xe ions of energy 0.9 MeV/ N, 84Kr ions of energy 0.9 MeV/ N and 56Fe ions of energies 5.1 MeV/ N, 3.3 MeV/ N, 2.4 MeV/ N and 1.3 MeV/ N from the Joint Institute of Nuclear Research (JINR), Dubna, USSR. These irradiated samples have been etched in 40 vol.% HF at 30°C. The etch pit diameter against etching time has been measured and the total etchable track length has been determined for these ions in this detector. The energy loss and range of these ions in quartz glass have also been computed theoretically. Comparing the value of the total etchable track length with the theoretically computed value of the range, the critical threshold for etchable track formation in quartz glass has been found. An attempt to find the charge resolution of this detector has also been made.

Study of heavy ion tracks in different samples of cellulose nitrate

Samples of cellulose nitrate Daicel (Japanese) and cellulose nitrate (Russian) have been exposed to 40Ar ions of energy 7.4. MeV/N and 50Ti ions of energy 4.9 MeV/N respectively at an angle of 30° from the detector surface using heavy ion cyclotron facilities at JINR Dubna (Moscow), USSR. These samples have been etched in 6.25N NaOH at 60°C. The bulk etch rate V b has been found at different etching temperatures to determine the activation energies for bulk etching for these plastics. The variation of track length against etching time has been studied to find out the values of total etchable track length for these ions in these detectors. The energy loss and ranges of these ions in these plastics have been computed theoretically. By the comparison of the total etchable track length with the respective value of the theoretically computed range, the values of the critical threshold for these plastics have been found. Finally an attempt has been made to compare the response of these two plastics.

Study of heavy ion tracks in soda glass

The pre-annealed and pre-etched samples of a soda glass detector are irradiated to 50Ti, 56Fe and 129Xe beams of energy 4.9 MeV/N, 5.1 MeV/N and 0.9 MeV/N, respectively from the Joint Institute of Nuclear Research (JINR) Dubna (Moscow) USSR. These irradiated samples are etched in the new etchant (HF 48 vol.% + H2SO4 96 vol.% + H2O in the ratio of 6:1:18 with small amount of Zn) at 40°C. The etch pit diameter and track length are measured for different etching times. The energy loss and range of these ions in soda glass are also computed theoretically. By the comparison of total etchable track length with the theoretical range, the value of critical threshold for etchable tracks in soda glass is found to be (13.0 ± 1) MeV mg−1cm2.

On the measurement of the momentum of 19 GeV/ c electrons in a heavy liquid bubble chamber

The Fermilab 15-ft bubble chamber was exposed to an electron beam of 19 GeV/ c momentum. The chamber was filled with a heavy neon-hydrogen mixture (64% atomic Ne, 36% atomic H) and operated with a magnetic field of 3 T. The momentum of the electrons was determined from the bubble chamber pictures using two methods: (a) the measurement of the curvature of the electrons and their shower products, and (b) the measurement of the total track length of the electron and its shower. The momentum, as determined from curvature measurement of the primary electron and the e +e − pairs from the radiated gammas was 19.1±7.6 GeV/c.

Scintillation light from liquid argon and its use in a new hybrid detector

Scintillation light, produced by 200 MeV/c pions in a liquid argon bubble chamber/calorimeter was measured. Results from the test device show that this signal could be used in future large bubble chambers to trigger the flash on the occurrence of an interesting event. Furthermore, this signal give rough information about total track lengths, hence energy contained in massive electromagnetic and hadronic showers, and could complement measurements obtained by charge collection.

Calculation of released energy and total track lengths of charged particles in showers in xenon

Calculation of released energy and total track lengths of charged particles in showers in xenon

Characteristics of fission tracks in zircon: Applications to Geochronology and Cosmology

We describe a simple method for nearly isotropic revelation of fission tracks in zircon. The etchant is an equivolume mixture of 48% HF and 98% H 2SO 4; etching is carried out under pressure at 150° – 180°C. For fossil track densities above ∼ 5 × 10 6, the etching time is strongly anticorrelated with track density. The total etchable fission fragment track length (2 fragments) is 11 ± 0.5 μm. The length distribution is sharply peaked; the standard deviation in different samples is ± (0.7 – 0.8) μm. Thermal annealing studies indicate a lower activation energy for track fading than was previously repoted using a phosphoric acid etchant. A practical chemical dissolution method is described for quantitatively recovering zircon crystals from rock samples; this method should find application in fission track dating of even zircon poor rocks.

Characteristics of tracks of ions of 14⩽Z⩽36 in common rock silicates

This paper concerns the identification of heavy ion tracks in minerals by measurements of track-etch rates and total etchable track lengths. With beams of Si, Cl, Ti, Fe, Zn and Kr at energies up to 10.35 MeV/nucleon we have irradiated nine minerals commonly used to study fossil cosmic ray tracks in meteorites and lunar samples. From our measurements of etched track length as a function of residual range, we have determined response curves for various minerals as a function of ionization rate, using the expression previously derived by Price, Fleischer and Moak. These curves increase smoothly with ionization rate instead of rising abruptly at some critical value as was previously thought. We have shown that the track etch rate concept accounts qualitatively for total etchable track length distributions, but that the positions of the peaks of different elements in these histograms occur at shorter lengths for fossil tracks than for fresh tracks. Our annealing data indicate that, at maximum lunar surface temperatures, tracks in olivine, orthopyroxenes and feldspars may be significantly shortened whereas tracks in clinopyroxenes will not be affected. We cite additional evidence that gradual rearrangement of radiation damage at ambient temperature makes the properties of fresh tracks and of ancient tracks different. It is thus not surprising that the histograms of fresh and fossil tracks do not match perfectly.

Growth inhibition in cereal seedlings induced by gamma irradiation at different oxygen tensions

The reaction of barley and rye seeds to anaerobic and aerobic γ-irradiation was studied, with special emphasis on such properties where the action of neutrons has been found qualitatively different from that of (aerobic) γ-or X-irradiation. The reaction of anaerobic γ-irradiation was found similar to that of neutrons, and unlike that of aerobic γ-irradiation, in the following respects: (a) a more linear dose dependence of the radiation induced growth inhibition of seedlings; (b) a relatively greater inhibition of root growth; (c) a smaller variation of seedling heights; the coefficient of variation of seedling height following anaerobic γ-irradiation or neutron irradiation is equal to that of the unirradiated control samples; after aerobic γ-irradiation (in air or in high pressure oxygen) the coefficient of variation at 50 per cent growth reduction is 2–3 times the control value; (d) no influence of the water content of the seeds on their radiation sensitivity, within the range of water contents investigated (6–20%) (indicated in comparison of different experiments). The findings are discussed in the light of investigations of especially H oward-F landers (19) and C aldecott (6), demonstrating that in the absence of oxygen, the γ-irradiation is active exclusively through high LET segments of the total track length, i.e. chiefly through δ-rays. RBE of fission neutrons relative to anaerobic γ-radiation is found to be around 50.

Coherent production of pions by high-energy pions on complex nuclei

A search was made in nuclear emulsion for examples of coherent multiple production of pions by diffraction dissociation and Coulomb dissociation. The primary particles were negative pions of 14, 16.2 and 17 GeV/c, and the total track length examined was 971.8 m. Events in which there were three fast charged secondaries and no evidence of disintegration or radioactive decay of the target nucleus were found to contain a large proportion of possible examples of coherent production. This conclusion could be reached without the use of measurements of the momenta of the secondaries. A more detailed analysis was carried out with the aid of the results of momentum determinations, and this led to an estimate of the mean free path of (51−11+18) metres of emulsion for the coherent reaction π−+nucleus→π−+π−+π++ nucleus. An analysis of the distributions of momentum transfer to the target nucleus, as well as a comparison with the results of the bubble-chamber work, provide strong indications that all the complex nuclei in the emulsion act as targets in this reaction, and the results are fully consistent with the hypothesis that diffraction dissociation is the dominant mechanism.

The Distribution of Energy in the Electron-Photon Component of Extensive Air Showers

An array of four water Cerenkov detectors of variable depth (maximum 3.4 radiation lengths) has been used to study extensive air showers of size 105 to 106 particles. The amount of Cerenkov light produced is a measure of the total electron track length in the detectors resulting from the incident spectrum of electrons and photons. The difference between the lateral structure function as measured by the Cerenkov detectors and the known particle density distribution function is therefore related to the presence of cascading or attenuation in the water. This was confirmed by observations with Geiger counters above and below a detector. These effects in the water are thus a measure of the energy of the electron-photon component. The energy carried by this component per shower electron was found to vary between 440 ± 60 MeV at a distance of 2 m from the shower axis and 195 ± 35 MeV at 12 m distance. The part of this energy which is carried by photons was found to be greater than that carried by electrons throughout most of the region examined.

Energy Distribution in Low-Energy Electron-Photon Showers in Lead Absorbers

S>Detailed results for the energy distribution in electronphoton showers developing in lead absorbers are presented for the cases of primiry electrons and photons of energy Wilson's calculations on the same subject gave too low- an energy degradation for electrons, thus making his electron numbers far too high. The total track length of electrons of energy > 10 Mev for either electron or photon primaries is given by T = 0.032E/sub 0/ radiation lengths with E/sub 0/ in Mev. It is also found that: (a) The average energy of the individual electrons lost because their energy is 10 Mev is 14.0 Mev; (d) the average energy of backscattered photons with E > 10 Mev is 13.1 Mev; (e) the average number of all photonis produced per electron track length is 11.04. (auth)

THE PRODUCTION OF HIGH-ENERGY KNOCK-ON ELECTRONS AND BREMSSTRAHLUNG BY μ-MESONS

A multiplate cloud chamber experiment has been carried out to study the electromagnetic interactions of μ-mesons in iron and lead target materials. Energetic interactions which occurred inside the chamber were selected by an arrangement of plastic scintillators and Geiger counters; the total track lengths, and hence the energies, of the associated electron showers were measured by a photometric method combined with scintillator measurements. When Bremsstrahlung is the dominant process, the measured production probabilities are in good agreement for energy transfers in the range from about 8 to 40 Bev. When the production of knock-on electrons is the dominant process, good agreement with theory is obtained for energy transfers around 4.5 Bev but only fair agreement is obtained for higher energy transfers.

Investigation into the Elastic Scattering ofΣ±Hyperons on Hydrogen

An investigation has been made into the elastic scattering of $\ensuremath{\Sigma}$ hyperons on hydrogen. The experiment was based on a sample of 12 000 $\ensuremath{\Sigma}$ particles formed in a propane bubble chamber by the interactions of 1.15-Bev/c ${K}^{\ensuremath{-}}$ mesons. A total track length of 210 meters in the energy range 100 to 700 Mev has been examined.Ten examples were found of the reaction ${\ensuremath{\Sigma}}^{+}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{+}+p$, and six of the reaction ${\ensuremath{\Sigma}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{\ensuremath{-}}+p$. The estimates of the cross sections for the two processes are, respectively, ${38}_{\ensuremath{-}14}^{+18}$mb and ${10}_{\ensuremath{-}4}^{+6}$mb. The scattering angle distributions in the c.m. system appear isotropic for the ${\ensuremath{\Sigma}}^{+}$ particles, and peaked forward for the ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ particles. The results are discussed in relation to various theoretical predictions, and, in particular, some evidence is found favoring the Gammel-Thaler method of treating the triplet odd-parity nucleon-nucleon potential.

Quantitative Relation of RBE in Tradescantia and Average LET of Gamma-Rays, X-Rays, and 1.3-, 2.5-, and 14.1-Mev Fast Neutrons

The relative effectiveness of Co/sup 60/ %gg-rays, x-rays, and 14-Mev D, T. 2.5-Mev D, D, and cyclotron 1-Mev average-energy fast neutrons in causing chromosomal aberrations in the plant Tradescantia have been compared. A conservative estimate of the over-all accuracy in these experiments is 15% for physical values. 20% for biological values. and 2% for average LET values as defined here: it is believed that actually the over-all accuracy for all three factors is considerably better than this. Track average and energy average LET's are derived for each radiation in order to make comparisons of RBE against LET. The assignment of proper LET values and subsequent comparisons are relatively simple and straightforward when the ionization generated in tissue is substantially homogeneous. When tissue ionization is not homogeneous, but is made up of components of quite different average LET, the comparison is more complex because each separate component contributes a different relative amount to total dose, total track length, and total biological effect. For these cases. the biological and physical role of each component should be considered separately. RBE was compared against average LET for the radiations used, and to higher LET of alpha -particles and the heavy particles from the D,more » T neutron irradiation. RBE increases smoothly and about sevenfold from gamma -rays to 1- Mev average-energy cyclotron neutrons (track average LET range from 0.27 to 27 kev/ mu ), peaks somewhere between 1-Mev fast neutrons and gamma -particles in the average LET range of 50 to 70 kev/ mu at an RBE of 8 to 11, and then falls toward the higher-LET alpha -particles and D. T heay particles. Within the fast- neutron energy range, from 14-Mev D. T to 1-Mev cyclotron to 2.5-Mev D, D. neutrons (track average LET of 12, 27, and 31 kev/ mu ), RBE increases threefold. The shape of the curve of RBE against LET for chromosomal aberrations, an effect that may be considered as cellular cytogenetic lethality, is very similar to the curve for a galaxy of mammalian effects including lethality. In absolute amount, chromosomal RBE's are greater than those for mammalian lethality. (auth)« less

Production ofKMesons and Hyperons in Hydrogen by 1.95-Bev Protons

A search has been made for K mesons and hyperons produced by a well- collimated beam of 1.95-Bev protons in a hydrogen-filled diffusion chamber. One case of associated production was observed, which is interpreted as p + p yields DELTA /sup o/ + K/sup +/ + p. In a total track length of 2.4 x 10/sup 5/ g/cm/ sup 2/ of hydrogen, no other hyperons or K mcsons were observed to be produced. It is concluded that the cross section for production of K mesons and hyperons is probably less than 0.4 mb. (auth)

On the trident cross-section between 1 and 10 GeV

An estimate has been made of the trident cross-section for electrons of energy between 1 and 10 GeV. Energy determinations were made by scattering measurements on each track under conditions where the effects of spurious scattering have been shown to be negligible. In a total track length of 219 cm, the estimated number of true tridents was found to be 3, as compared with 2.4 expected from theory. Even on the basis of this small number of events, there is a marked discrepancy between our results and those of previous experiments at high energies. Eeasons for this discrepancy are discussed.