| 1. |
- Wall, Göran, 1951-
(författare)
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Exergy - a useful concept within resource accounting
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Anxiety concerning the problems of energy and resources hasled to a rapid increase in the interest in describing andunderstanding the conversion processes of energy and otherresources in society. To be able to understand the procedure ofthese conversion processes it is important that useful conceptsare available. I hope that this report will be a help in thedevelopment of such concepts.
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| 2. |
- Bergström, Lars, et al.
(författare)
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Estimates of recoil nucleon spectra in high-energy hadron-nucleus collisions
- 1977
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 68:2, s. 177-179
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that recent data on the recoil nucleon spectrum in 10.5 GeV/c pion-neon collisions are in excellent agreement with a parameter free estimate from the so called tube model for high-energy hadron-nucleus collisions. A simple independent collision model is also treated.
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| 3. |
- Bergström, Lars, et al.
(författare)
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Is the recently published counterproof of the tube model credible?
- 1978
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 78:2-3, s. 337-341
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that recent data from pion and proton collision with emulsion nuclei at 200 GeV/c are in perfect agreement with expectations from the collective tube model. The opposite conclusion in publications by Azimov et al. came about because the authors ignored the important effects of target fragmentation.
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| 4. |
- Fredriksson, Sverker
(författare)
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A phenomenological two-component picture of large transverse momentum production
- 1976
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 63:3, s. 321-323
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Tidskriftsartikel (refereegranskat)abstract
- It is suggested that large-pT hadrons can be classified into two categories with completely different properties according to whether they contain a leading quark or just sea quarks from the initial projectile-target system. From simple quark counting we get relations between hadron ratios at large pT, which are consistent with data.
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| 5. |
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| 6. |
- Fredriksson, Sverker
(författare)
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Large-pT π0 Production in High-Energy πp Collisions
- 1976
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 37:21, s. 1373-1374
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Tidskriftsartikel (refereegranskat)abstract
- It is pointed out that the recently measured difference in pT spectrum between π±p→π0X and pp→π0X, with a large-pT π0, seems to be a consequence only of the smaller number of quarks per projectile in a pion beam.
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| 7. |
- Fredriksson, Sverker
(författare)
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On large transverse momentum production in high-energy proton-nucleus collisions
- 1976
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Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 111:1, s. 167-177
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Tidskriftsartikel (refereegranskat)abstract
- Experimental data from inclusive production of large pT hadronsin high-energy proton-nucleus collisions are analysed with emphasis on the influence of the size of the target nucleus. It is found that data at pT≤3 GeV/c are consistent with the hypothesis that the incoming proton collides "simultaneously" with all the nucleons in its way, resulting in an effective collision energy larger than the one expected in a single proton-nucleon hit. At pT > 3 GeV/c, data are in conflict with such a simple model, a result we think is a consequence of the dominance of hard parton collisions at very large pT.
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| 8. |
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| 9. |
- Fredriksson, Sverker
(författare)
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Phenomenological relations between large-pT meson spectra
- 1978
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Ingår i: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 18:11, s. 4144-4151
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Tidskriftsartikel (refereegranskat)abstract
- Recent data on the hadron ratios π+π-, K+π+, K-π-, and ηπ0 at large transverse momenta are shown to be consistent with predictions from a simple phenomenological two-component picture for large-pT production. The very-large-pT part of meson spectra is assumed to be dominated by particles that contain one of the incoming valence quarks, while small-and medium-pT mesons are built up mostly of quarks created in quark-antiquark pairs. Exceptions are K- and φ spectra, where for obvious reasons the very-large-pT component is missing. Simple relations between π, K, and η spectra are found. Predictions for the large-pT spectrum of φ mesons are presented.
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| 10. |
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| 11. |
- Fredriksson, Sverker
(författare)
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The collective tube model and how to disprove it
- 1979
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Ingår i: First workshop on ultra-relativistic nuclear collisions. - Berkeley, Calif : Lawrence Berkeley National Laboratory.
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Konferensbidrag (refereegranskat)
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| 12. |
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| 13. |
- Andersson, B., et al.
(författare)
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The relationship between the meson, baryon, photon and quark fragmentation distributions
- 1977
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 69:2, s. 221-224
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Tidskriftsartikel (refereegranskat)abstract
- The ideas presented in an earlier note on the relationship between the quark fragmentation distributions as measured in leptoproduction and the one particle distributions in the mesonic fragmentation regions of hadronic interactions are carried further to photoproduction and to the baryon fragmentation distributions. The results are as before interpreted in terms of a simple additive quark model where the main interaction is due to the wee partons whereas almost all the initial momentum is carried by one of the valence quarks or a diquark.
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| 14. |
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| 16. |
- Gustafson, Gösta, et al.
(författare)
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Rescattering effects in the decay of the A1
- 1976
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 116:2, s. 301-316
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Tidskriftsartikel (refereegranskat)abstract
- Rescattering effects in the 3π system in the A1 region are studied with a method, which fulfils unitarity and has the proper analytic structure. Fairly small effects are obtained which confirm the result found in amplitude analyses, neglecting rescattering corrections, that the phases of the JP = 1+ amplitudes vary only very little over the A1 region. Similar results hold for the Q enhancement.
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| 17. |
- Hammersberg, Peter
(författare)
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Techniques for the determination of the optimal performance of high resolution computerised tomography
- 1977
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Techniques to deternine the optimal performance of high resolution computerised tomography (CT) has been studied, that is, optimal data collection parameter settings for the imaging task at issue and its detectability limits.Generally, CT is an X-ray based non-destructive testing method that was developed for medical purposes in the seventies and introduced for industrial applications the latter half of the eighties. CT produces maps of the X-ray linear attenuation coefficient of an object's interior; it is presented either as cross section images (two-dimensional CT) or as volume information (three-dimensional CT). The linear attenuation coefficient is the absorption and scatter of X-rays per length as it propagates through an object. The linear attenuation coefficient depends on the X-ray photon energy, and both object density and atomic composition.Most industrial CT-systems are equipped with conventional X-ray tubes that produce X-ray photons with an energy distribution, that is, a spectrum. Consequently, the effective linear attenuation coefficient of an object, shown by CT, depends on the full energy spectrum, how it changes as it propagates through the object, and how it interacts with the detector. To emphasise contrasts in the final CT-image, caused by density or compositional variations in the object investigated, the energy spectrum has to be chosen and shaped with filters in a way so that the differences in effective linear attenuation coefficient increase. However, it is empirically tedious to find optimal CT parameter settings, particularly for industrial CT, because of the wide range of materials, applications, and imaging tasks of interest.The main result from this work is the simulation model of the data collection process that makes it possible to determine optimal operator parameter settings that maximise the detectability for an arbitrary imaging task and predict its detectability limits. The simulation model can be used to correct for beam hardening artefacts in CT-images.There are several important partial results: (1) definition of quality of the CT-data in relation to the imaging task, including a model of the X-ray paths and how it is used to predict the optimal performance; (2) a model and method to determine how the information of the imaged object transfer from the detector entrance screen through the detector chain to CT projection data and further on to the final CT image. without detailed knowledge of each stage in the detector chain; (3) a model and method of how the total unsharpness of the CT-system is determined, in terms of modulation-transfer-function as a function of spatial frequency; and (4) the commonly used contrast-detail-curve, together with the limiting perception factor for detection of small details, is developed here to the more useful object detail-detectability curve.It has been shown that to model the data collection process for CT, a polyenergetic model is needed. Such a model consists of: complete X-ray energy spectra that are produced by the X-ray source used and a detector response model of how the X-rays impart energy to the detector entrance screen. Absolute X-ray spectra were measured using a Compton spectrometer. The detector response was determined using Monte Carlo photon transport simulations. It is further shown that X-ray source leak radiation increases image noise when the generated X-ray spectrum contains photons with energies over the K-edges of the enclosure wall material.
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| 21. |
- Akselsson, Roland, et al.
(författare)
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Elemental Abundance Variation with Particle Size in Aerosols from Welding Operations
- 1974
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Ingår i: Proceedings of the Second International Conference on Nuclear Methods in Environmental Research. ; , s. 395-401
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Konferensbidrag (refereegranskat)abstract
- The effect of airborne particulate matter on human health is today of considerable research interest. Essential parameters include elemental composition sampling with low pressure cascade impactors and analysis by particle induced x-ray emission spectroscopy (PIXE). It is shown that the aerosol generated by arc welding operations is several orders of magnitude denser than aerosols in ambient air. Most of the mass is found on particles between 0.1 and 1µm diameter, but the size distribution differs from one welding technique to another. The relative composition of the aerosol is found to differ significantly from that of both the welding piece and the electrode indicating the presence of fractionation of the type indicated in this work in designing electrodes and welding pieces to minimize the health hazards associated with the welding.
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| 26. |
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| 27. |
- Lannefors, Hans, et al.
(författare)
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Grundämnessammansättning i olika partikelstorleksfraktioner av den atmosfäriska aerosolen
- 1978
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Beskrivning ges av analysteknik (protoninducerad röntgenstrålning), provtagningsteknik (kaskadimpaktor av Battelle-typ) och provberedningsteknik. Utfört arbete i form av provbehandlingsförbättringar, konstruktion och förbättring av provtagare, bestämning av lämpliga analysparametrar samt uppbyggnad av ett dataprogramsystem presenteras. Sammanställning av resultat i form av beräknade medelvärden i klasser efter luftmassans historia redovisas.
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| 28. |
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