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- Abazov, M, et al.
(author)
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Search for Charged Higgs Bosons Decaying into Top and Bottom Quarks in pp Collisions
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:19, s. 191802-
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Journal article (peer-reviewed)abstract
- We describe a search for production of a charged Higgs boson, qq>-> H+, reconstructed in the tb final state in the mass range 180 <= M-H(+)<= 300 GeV. The search was undertaken at the Fermilab Tevatron collider with a center-of-mass energy s=1.96 TeV and uses 0.9 fb(-1) of data collected with the D0 detector. We find no evidence for charged Higgs boson production and set upper limits on the production cross section in the types I, II, and III two-Higgs-doublet models (2HDMs). An excluded region in the (M-H(+), tan beta) plane for type I 2HDM is presented.
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| 2. |
- Kaveckyte, Vaiva, et al.
(author)
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Monte Carlo characterization of high atomic number inorganic scintillators for in vivo dosimetry in Ir-192 brachytherapy
- 2022
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In: Medical physics (Lancaster). - : WILEY. - 0094-2405 .- 2473-4209. ; 49:7, s. 4715-4730
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Journal article (peer-reviewed)abstract
- BackgroundThere is increased interest in in vivo dosimetry for 192Ir brachytherapy (BT) treatments using high atomic number (Z) inorganic scintillators. Their high light output enables construction of small detectors with negligible stem effect and simple readout electronics. Experimental determination of absorbed-dose energy dependence of detectors relative to water is prevalent, but it can be prone to high detector positioning uncertainties and does not allow for decoupling of absorbed-dose energy dependence from other factors affecting detector response .PurposeTo investigate which measurement conditions and detector properties could affect their absorbed-dose energy dependence in BT in vivo dosimetry.MethodsWe used a general-purpose Monte Carlo (MC) code PENELOPE for the characterization of high-Z inorganic scintillators with the focus on ZnSe () Z. Two other promising media CsI () and Al2O3 () were included for comparison in selected scenarios. We determined absorbed-dose energy dependence of crystals relative to water under different scatter conditions (calibration phantom 12 × 12 × 30 cm3, characterization phantoms 20 × 20 × 20 cm3, 30 × 30 × 30 cm3, 40 × 40 × 40 cm3, and patient-like elliptic phantom 40 × 30 × 25 cm3). To mimic irradiation conditions during prostate treatments, we evaluated whether the presence of pelvic bones and calcifications affect ZnSe response. ZnSe detector design influence was also investigated.ResultsIn contrast to low-Z organic and medium-Z inorganic scintillators, ZnSe and CsI media have substantially greater absorbed-dose energy dependence relative to water. The response was phantom-size dependent and changed by 11% between limited- and full-scatter conditions for ZnSe, but not for Al2O3. For a given phantom size, a part of the absorbed-dose energy dependence of ZnSe is caused not due to in-phantom scatter but due to source anisotropy. Thus, the absorbed-dose energy dependence of high-Z scintillators is a function of not only the radial distance but also the polar angle. Pelvic bones did not affect ZnSe response, whereas large and intermediate size calcifications reduced it by 9% and 5%, respectively, when placed midway between the source and the detector.ConclusionsUnlike currently prevalent low- and medium-Z scintillators, high-Z crystals are sensitive to characterization and in vivo measurement conditions. However, good agreement between MC data for ZnSe in the present study and experimental data for ZnSe:O by Jørgensen et al. (2021) suggests that detector signal is proportional to the average absorbed dose to the detector cavity. This enables an easy correction for non-TG43-like scenarios (e.g., patient sizes and calcifications) through MC simulations. Such information should be provided to the clinic by the detector vendors.
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