| 1. |
|
|
| 2. |
- Barucca, G., et al.
(författare)
-
Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
-
Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
-
Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
|
|
| 3. |
- Barucca, G., et al.
(författare)
-
The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
-
Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
-
Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
|
|
| 4. |
|
|
| 5. |
- Morabito, R, et al.
(författare)
-
Towards a new Certified Reference Material for butyltins, methylmercury and arsenobetaine in oyster tissue
- 2004
-
Ingår i: TRAC-TRENDS IN ANALYTICAL CHEMISTRY. - : Elsevier BV. - 0165-9936. ; 23:9, s. 664-76
-
Tidskriftsartikel (refereegranskat)abstract
- Increasing awareness of the determination of chemical species in the environment evolves jointly with the need to control the validity of analytical measurements in a wide variety of matrices. There are few Certified Reference Materials (CRMs) available for various chemical species, and they are certified for species of one single element (e.g., species of tin and mercury). Three years of collaboration within the framework of European Commission research programmes involving more than 20 laboratories have made it possible to produce an oyster reference material for species of tin, mercury and arsenic (BCR-710) and to perform the necessary experimental work for its certification. This article summarises the feasibility study and describes the various steps in the preparation, production and characterisation of this material for its content of arsenobetaine, methylmercury, tributyltin and dibutyltin. These steps included stability and homogeneity testing as well as value assignment based on a collaborative approach involving a group of European laboratories. Further work is going on to certify total contents for a range of trace metals.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Frech, Wolfgang, et al.
(författare)
-
Characterization of a pressurizable two-step atomizer for atomic absorption spectrometry
- 2000
-
Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. ; 55:5, s. 461-72
-
Tidskriftsartikel (refereegranskat)abstract
- A two-step atomizer consisting of a transversely heated atomization tube with integrated contacts and a cup furnace for sample vaporization was constructed. The system could accommodate tubes of various lengths and it could be operated at selected pressures. There was no physical contact between the tube and the cup and mainly diffusion was responsible for the sample vapour transport from the cup to the tube. Under these conditions there was an unavoidable loss by 40% of the peak area signals due to the gap between the cup and the tube. For a 24-mm tube, characteristic masses were on the average three times lower than for the state of the art transverse heated graphite atomizers (THGA). By de-coupling the processes of analyte vaporization and atomization the dynamic working range could be increased by three to six times using conventional measurements by atomic absorption spectrometry (AAS). In this case the cup temperature and hence the rate of analyte transport from the cup to the tube was controlled such that atom density in the tube did not exceed the linear range of the absorbance measurement. Carrying out clean-out steps at reduced pressure decreased memory effects.
|
|
| 9. |
- Hermann, G, et al.
(författare)
-
Platform-to-platform sample transfer, distribution, dilution, and dosing via electrothermal vaporization and electrostatic deposition
- 2004
-
Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. - : Elsevier BV. - 0584-8547. ; 59:5, s. 737-48
-
Tidskriftsartikel (refereegranskat)abstract
- A novel system for solid sample pretreatment, handling and dosing for analytical atomic spectrometry is described. A primary solid or liquid sample is vaporized in a graphite furnace and then condensed in a specially designed condensation zone. On the further transport path, the analyte aerosol can be diluted and distributed in pre-set ratios in the laboratory made flow control system. Applying a corona discharge, aerosol particulates are then quantitatively re-collected by means of intra-furnace electrostatic precipitation on the platform of another graphite furnace or by external precipitation on one or a set of platforms. This makes possible to produce a set of secondary platforms with equal analyte compositions from one individual primary sample. Such multitudes allow sequential multi-element determinations with single-element instrumentation or comparative measurements with different techniques. Furthermore, the described procedure allows external thermal sample pretreatment with preceding pyrolysis and additional vaporization, condensation, and re-precipitation that significantly reduces or removes the sample matrix. Owing to different losses, transport efficiencies of electrothermal vaporization (ETV) instrumentation depend on analyte element, matrix, vaporization temperature, ramp rate, and tube history. In order to reduce the losses and therewith such dependencies of the losses, new laboratory constructed ETV unit with analyte condensation in an axially focusing upstream convection zone has been constructed. Analytical performance of the new setup is compared with the performance of a commercial end-on flow-through ETV unit when analyzing both liquid dosed samples and certified solid reference materials. The new system shows much higher transport efficiencies that are, in addition, more uniform for elements of different volatility. The effects of chemical sample modifiers and elements supporting analyte condensation are studied. Most of the analytical measurements were carried out with a continuum source coherent forward scattering multi-element spectrometer. Comparative measurements were also carried out independently in the co-authors’ laboratories with atomic absorption and inductively coupled plasma mass spectrometry techniques.
|
|
| 10. |
|
|
