Učinak izbočine i analitičko produljenje kanalnih propagatora u višekanalnom formalizmu Cutkoskog u modelu dvaju tijela

Cutkosky coupled multichannel, and manifestly unitary model, reduced to three two-body coupled channels, has been used to predict eight lowest partial-wave T-matrices for the πN → ηN and ηN → ηN processes by the Zagreb-Los Angeles collaboration. The shape of the S11-wave cusp effect near η production threshold for the πN elastic scattering turned out to be wrong in the first analysis, and has been corrected by the Zagreb-Los AngelesArgonne update of the analysis. The shape error has been traced back to the numerically incorrect assumption of the input sign of the Cutkosky channel propagators. The details of the error, correct form of the input function and the correct analytical continuation of the channel propagators is presented.Izričito unitaran, Cutkoskyev model više vezanih kanala, primijenjen je u okviru Zagreb – Los Angeles suradnje na slučaj tri vezana dvočestična kanala i tako su dobivene πN → ηN i ηN → ηN T matrice za osam najnižih parcijalnih valova. Pokazalo se da je u prethodnoj analizi oblik izbočine u S11 πN elastičnoj T matrici u blizini praga za η produkciju bio kriv, i ispravljen je u novoj analizi koja je napravljena u suradnji Zagreb – Los Angeles – Argonne. Uzrok greške u obliku izbočine je u tome što je uzet kriv predznak u kanalnom propagatoru Cutkoskog. Iznesene su pojedinosti pogreške te je dobiven ispravan oblik i analitičko produljenje kanalnog propagatora

Učinak izbočine i analitičko produljenje kanalnih propagatora u višekanalnom formalizmu Cutkoskog u modelu dvaju tijela

Cutkosky coupled multichannel, and manifestly unitary model, reduced to three two-body coupled channels, has been used to predict eight lowest partial-wave T-matrices for the πN → ηN and ηN → ηN processes by the Zagreb-Los Angeles collaboration. The shape of the S11-wave cusp effect near η production threshold for the πN elastic scattering turned out to be wrong in the first analysis, and has been corrected by the Zagreb-Los AngelesArgonne update of the analysis. The shape error has been traced back to the numerically incorrect assumption of the input sign of the Cutkosky channel propagators. The details of the error, correct form of the input function and the correct analytical continuation of the channel propagators is presented.Izričito unitaran, Cutkoskyev model više vezanih kanala, primijenjen je u okviru Zagreb – Los Angeles suradnje na slučaj tri vezana dvočestična kanala i tako su dobivene πN → ηN i ηN → ηN T matrice za osam najnižih parcijalnih valova. Pokazalo se da je u prethodnoj analizi oblik izbočine u S11 πN elastičnoj T matrici u blizini praga za η produkciju bio kriv, i ispravljen je u novoj analizi koja je napravljena u suradnji Zagreb – Los Angeles – Argonne. Uzrok greške u obliku izbočine je u tome što je uzet kriv predznak u kanalnom propagatoru Cutkoskog. Iznesene su pojedinosti pogreške te je dobiven ispravan oblik i analitičko produljenje kanalnog propagatora

Izospinske korelacije u visoko energetskim sudarima teških iona

We study the possibility of large isospin fluctuations in high-energy heavy-ion collisions by assuming that pions are produced semiclassically both directly and in pairs through the isovector channel. The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to define the classical pion field. In terms of the joint probability function PII3 (n0, n ) for producing n0 neutral and n negative pions from a definite isospin state II3 of the incoming leading-particle system we calculate the two–pion correlation parameters f 0 2,n and the average number of neutral pions (hn0in ) as a function of negative pions (n ) produced. We show that only direct production of pions without isovector pairs leads to large isospin fluctuations.Uz pretpostavku da se pioni produciraju poluklasično, direktno i putem izovektorskih parova ispituje se mogućnost velikih izospinskih fluktuacija u sudarima teških iona kod visokih energija. Učinak vodećih čestica i faktorizacija amplitude raspršenja u prostoru parametra upada koristi se za definiciju klasičnoga pionskog polja. Pomoću raspodjelne funkcije PII3 (n0, n ) za produkciju n0 neutralnih i n negativno nabijenih piona iz odredenoga izospinskog stanja II3 ulaznog sistema vodećih čestica izračunat je dvopionski korelacioni parametar f 0 2,n i srednji broj neutralnih piona (n ) kao funkcije broja produciranih negativno nabijenih piona (n ). Pokazuje se da samo direktna produkcija piona bez izovektorskih parova vodi na velike izospinske fluktuacije

Izospinske korelacije u visoko energetskim sudarima teških iona

We study the possibility of large isospin fluctuations in high-energy heavy-ion collisions by assuming that pions are produced semiclassically both directly and in pairs through the isovector channel. The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to define the classical pion field. In terms of the joint probability function PII3 (n0, n ) for producing n0 neutral and n negative pions from a definite isospin state II3 of the incoming leading-particle system we calculate the two–pion correlation parameters f 0 2,n and the average number of neutral pions (hn0in ) as a function of negative pions (n ) produced. We show that only direct production of pions without isovector pairs leads to large isospin fluctuations.Uz pretpostavku da se pioni produciraju poluklasično, direktno i putem izovektorskih parova ispituje se mogućnost velikih izospinskih fluktuacija u sudarima teških iona kod visokih energija. Učinak vodećih čestica i faktorizacija amplitude raspršenja u prostoru parametra upada koristi se za definiciju klasičnoga pionskog polja. Pomoću raspodjelne funkcije PII3 (n0, n ) za produkciju n0 neutralnih i n negativno nabijenih piona iz odredenoga izospinskog stanja II3 ulaznog sistema vodećih čestica izračunat je dvopionski korelacioni parametar f 0 2,n i srednji broj neutralnih piona (n ) kao funkcije broja produciranih negativno nabijenih piona (n ). Pokazuje se da samo direktna produkcija piona bez izovektorskih parova vodi na velike izospinske fluktuacije

Estimated Absorbed Doses from Exposure to a Cyclotron Used in Production of Radiopharmaceuticals

Dijagnostički postupci i liječenje iz područja nuklearne medicine podrazumijevaju uporabu radionuklida ili radiofarmaceutika, tj. farmaceutika u kojima su radionuklidi vezani na druge, biološki aktivne kemijske spojeve, u svrhu njihova označivanja i praćenja distribucije radioobilježivača u živome biološkom sustavu. Specifi čnost radiofarmaceutika je u mogućnosti uporabe metoda nuklearne detekcije za prikazivanje vremenskog tijeka njihova prostornog nakupljanja u određenom organu, odnosno njihova ulaska u metaboličke procese. Na taj način njihovom uporabom moguće je prikazati funkcionalne promjene, za razliku od klasičnih radioloških pretraga s pomoću kojih se prikazuju morfološke promjene u organima. U ovom radu prikazane su izmjerene brzine doza γ-zračenja na pojedinim mjestima unutar proizvodnog postrojenja Ruđer Medikol Ciklotrona (RMC), koje rabi 18 megaelektronvoltni ciklotron Cyclone 18/9 HC. Navedene su očekivane brzine doza za djelatnike RMC-a po specifi čnim radnim zadacima i mjestima. Na osnovi procijenjenog vremena boravka radnika na tim lokacijama, procijenjena je godišnja apsorbirana doza. Rezultati mjerenja uspoređeni su sa zakonskim granicama i preporukama. Pokazuje se da je koncept minimalizacije izlaganja radioaktivnom zračenju – ALARA („As Low As Reasonably Achievable”), koje preporučuje hrvatski zakonodavac, maksimalno ispunjen za pogon RMC-a.Nuclear medicine diagnostics and therapy use radiopharmaceuticals, which are pharmaceuticals with radionuclides attached to the biologically active chemical compound with the purpose of marking it in order to follow its metabolism in a living organism. The basic advantage of using radiopharmaceuticals is that they can be monitored by nuclear methods and their deposition in a particular organ or metabolic processes followed over time. Unlike classical radiology, which shows only morphological changes in an organ, with radiopharmaceuticals we can follow their functional changes. This article discusses estimated occupational exposure of three workers to a cyclotron IBA Cyclone 18/9 at Ruđer Medikol Cyclotron Ltd. (RMC). The total absorbed annual dose is estimated to between 2.95 mSv and 6.77 mSv. The requirement of minimal exposure to any form of radiation – ALARA (“As Low As Reasonably Achievable.”), recommended by Croatian legislation, is fully met

Multichannel Anomaly of the Resonance Pole Parameters Resolved

Inspired by anomalies which the standard scattering matrix pole-extraction procedures have produced in a mathematically well defined coupled-channel model, we have developed a new method based solely on the assumption of partial-wave analyticity. The new method is simple and applicable not only to theoretical predictions but to the empirical partial-wave data as well. Since the standard pole-extraction procedures turn out to be the lowest-order term of the proposed method the anomalies are understood and resolved.Comment: 5 page

The detailed mechanism of the eta production in pp scattering up to the Tlab = 4.5 GeV

Contrary to very early beliefs, the experimental cross section data for the eta production in proton-proton scattering are well described if pi and only eta meson exchange diagrams are used to calculate the Born term. The inclusion of initial and final state interactions is done in the factorization approximation by using the inverse square of the Jost function. The two body Jost functions are obtained from the S matrices in the low energy effective range approximation. The danger of double counting in the p-eta final state interaction is discussed. It is shown that higher partial waves in meson-nucleon amplitudes do not contribute significantly bellow excess energy of Q=100 MeV. Known difficulties of reducing the multi resonance model to a single resonance one are illustrated.Comment: 10 pages, 5 figures, corrected typos in relation (3), changed content (added section with differential cross sections

eta N S-wave scattering length in a three coupled channel, multiresonance, unitary model

The S-wave scattering length for eta-N elastic scattering is extracted from the S-wave T-matrix in a three coupled channel, multiresonance unitary model. Results are compared with values already reported in literature which are obtained applying multichannel, but single resonance -- no background models. A dispersion among the previously published values of the real part of the S-wave scattering length is observed. We demonstrate that the reported spread originates from the strong sensitivity of the scattering length upon the small variation of the used input resonance parameters. In addition, we show that eta-N scattering length value obtained in single resonance -- no background models significantly increases if background term is added in a unitary way. We question the reliability of previously reported values based only on the single resonance -- no background models, and demonstrate that the value of the eta-N S-wave scattering length obtained in this publication is much more realistic because of the multiresonance and unitary approach.Comment: revtex, 20 pages + 3 figures (PostScript: gzip + uuencode) included, submitted to Phys. Rev. C, brief Reports