32 research outputs found
Light response of pure CsI calorimeter crystals painted with wavelength-shifting lacquer
We have measured scintillation properties of pure CsI crystals used in the
shower calorimeter built for a precise determination of the pi+ -> pi0 e+ nu
decay rate at the Paul Scherrer Institute (PSI). All 240 individual crystals
painted with a special wavelength-shifting solution were examined in a
custom-build detection apparatus (RASTA=radioactive source tomography
apparatus) that uses a 137Cs radioactive gamma source, cosmic muons and a light
emitting diode as complementary probes of the scintillator light response. We
have extracted the total light output, axial light collection nonuniformities
and timing responses of the individual CsI crystals. These results predict
improved performance of the 3 pi sr PIBETA calorimeter due to the painted
lateral surfaces of 240 CsI crystals. The wavelength-shifting paint treatment
did not affect appreciably the total light output and timing resolution of our
crystal sample. The predicted energy resolution for positrons and photons in
the energy range of 10-100 MeV was nevertheless improved due to the more
favorable axial light collection probability variation. We have compared
simulated calorimeter ADC spectra due to 70 MeV positrons and photons with a
Monte Carlo calculation of an ideal detector light response.Comment: Elsevier LaTeX, 35 pages in e-print format, 15 Postscript Figures and
4 Tables, also available at
http://pibeta.phys.virginia.edu/~pibeta/subprojects/csipro/tomo/rasta.p
Design, Commissioning and Performance of the PIBETA Detector at PSI
We describe the design, construction and performance of the PIBETA detector
built for the precise measurement of the branching ratio of pion beta decay,
pi+ -> pi0 e+ nu, at the Paul Scherrer Institute. The central part of the
detector is a 240-module spherical pure CsI calorimeter covering 3*pi sr solid
angle. The calorimeter is supplemented with an active collimator/beam degrader
system, an active segmented plastic target, a pair of low-mass cylindrical wire
chambers and a 20-element cylindrical plastic scintillator hodoscope. The whole
detector system is housed inside a temperature-controlled lead brick enclosure
which in turn is lined with cosmic muon plastic veto counters. Commissioning
and calibration data were taken during two three-month beam periods in
1999/2000 with pi+ stopping rates between 1.3*E3 pi+/s and 1.3*E6 pi+/s. We
examine the timing, energy and angular detector resolution for photons,
positrons and protons in the energy range of 5-150 MeV, as well as the response
of the detector to cosmic muons. We illustrate the detector signatures for the
assorted rare pion and muon decays and their associated backgrounds.Comment: 117 pages, 48 Postscript figures, 5 tables, Elsevier LaTeX, submitted
to Nucl. Instrum. Meth.
Evaluation of the prognostic and predictive value of HER family mRNA expression in high-risk early breast cancer: A Hellenic Cooperative Oncology Group (HeCOG) study
The aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the HER family genes in early breast cancer, as well as to investigate the predictive value of HER2 mRNA expression for adjuvant treatment with paclitaxel. RNA was extracted from 268 formalin-fixed paraffin-embedded (FFPE) tumour tissue samples of high-risk breast cancer patients enrolled in the randomised HE10/97 trial, evaluating the effect of dose-dense anthracycline-based sequential adjuvant chemotherapy with or without paclitaxel. The mRNA expression of all four HER family members was assessed by kinetic reverse transcription-polymerase chain reaction (kRT-PCR). The overall concordance between kRT-PCR and IHC/FISH for HER2 status determination was 74%. At a median follow-up of 8 years, multivariate analysis showed that EGFR and HER2 mRNA expression was associated with reduced overall survival (OS). HER3 and HER4 mRNA level had a favourable prognostic value in terms of OS and disease-free survival (DFS), respectively. Adjusting for HER2 mRNA expression, OS and DFS did not differ between treatment groups. These data indicate that EGFR as well as HER2 are prognostic factors of worse clinical outcomes, whereas HER3 and HER4 gene transcription is associated with better prognosis in high-risk early breast cancer. However, HER2 mRNA expression did not predict clinical benefit from paclitaxel. Kinetic RT-PCR represents an alternative method for evaluating the expression of HER family members in FFPE breast carcinomas. © 2008 Cancer Research