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| 2. |
- Barucca, G., et al.
(författare)
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Feasibility studies for the measurement of time-like proton electromagnetic form factors from (p)over-barp -> mu(+)mu(-) at PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - NEW YORK, USA : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:1
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, vertical bar G(E)vertical bar and vertical bar G(M)vertical bar, using the (p) over barp -> mu(+)mu(-) reaction at PANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at PANDA, using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is (p) over barp -> pi(+)pi(-), due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented.
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| 3. |
- Barucca, G., et al.
(författare)
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PANDA Phase One
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:6
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Tidskriftsartikel (refereegranskat)abstract
- The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future antiProton ANnihilations at DArmstadt (PANDA or PANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton-nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model, e.g. through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the Phase One setup. The physics programme that is achievable during Phase One is outlined in this paper.
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| 4. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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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.
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| 5. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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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.
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| 6. |
- Cederwall, Hans
(författare)
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Bottendöden breder ut sig
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- De senaste betydande inflödena av syrerikt vatten från Västerhavet skedde under 1993-1994. Syresättningen av djupvattnet ledde till en nyrekrytering av bottendjur till stora områden som då saknade makroskopiskt liv. Under den efterföljande stagnationsperioden har djurlivet åter successivt utarmats och slagits ut, först på de största djupen, sedan allt grundare. Nedan följer en redogörelse för utvecklingen i Egentliga Östersjöns bassänger efter 1994, med vissa tillbakablickar till tidigare år.
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| 7. |
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| 8. |
- Cederwall, Hans
(författare)
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Förslag till program för nationella provningsjämförelser av marin mjukbottenfauna
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I arbetet med denna rapport har ingått att ta del av närliggande länders eventuella program för provningsjämförelser. Det visade sig att inget av de nordiska länderna har ett fungerande program för provningsjämförelser av mjubottenlevande marin makrofauna. Av Östersjöländerna har endast Tyskland ett utvecklat och sedan år 2000 fungerande system. För västerhavets del har Storbrittanien ett välutvecklat system som fungerat i 15 år. Såväl det tyska som det brittiska systemet har studerats och bildat underlag för slutsatserna i denna rapport. Som underlag har även erfarenheterna från tidigare internationella interkalibreringar (Ankar 1976, Ankar m fl 1978, HELCOM 1991) och en tidigare nationell (Cederwall 2002) använts.
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| 9. |
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| 10. |
- Cederwall, Hans
(författare)
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Makrofauna mjukbotten, trend- och områdesövervakning, egentliga Östersjön
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vid årets provtagning kunde effekterna av saltvatteninbrottet under hösten 2002 och vintern 2003 märkas på att fauna nu åter fanns på station BY 5 (Bornholmsdjupet, 90 m).Huvudsakligen bestod faunan av havsborstmasken Harmothoe sarsi som fanns i en täthet av 28 ind/m2. Enstaka individ av havsborstmaskarna Polydora ciliata, Aricidea jeffreysi och Capitella capitata hittades också.Inga positiva effekter av saltvatteninbrottet kunde märkas i de övriga bassängerna. Tvärtom var situationen extremt dålig i såväl Västra Gotlandsbassängen som i Norra Centralbassängen. På stationerna utanför Stockholms skärgård saknades nu fauna till och med på stationer med djup runt 75 m.
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