Recently, a new scintillation material DSB: Ce3+ was announced. It can be produced in a form of glass or nano-structured glass ceramics with application of standard glass production technology with ...successive thermal annealing. When doped with Ce3+, material can be applied as scintillator. Light yield of scintillation is near 100 phe/MeV. Un-doped material has a wide optical window from 4.5eV and can be applied to detect Cherenkov light. Temperature dependence of the light yield LY(T) is 0.05% which is 40 times less than in case of PWO. It can be used for detectors tolerant to a temperature variation between -20° to +20°C. Several samples with dimensions of 15x15x7 mm3 have been tested for damage effects on the optical transmission under irradiation with γ-quanta. It was found that the induced absorption in the scintillation range depends on the doping concentration and varies in range of 0.5-7 m−1. Spontaneous recovery of induced absorption has fast initial component. Up to 25% of the damaged transmission is recuperated in 6 hours. Afterwards it remains practically constant if the samples are kept in the dark. However, induced absorption is reduced by a factor of 2 by annealing at 50°C and completely removed in a short time when annealing at 100°C. A significant acceleration of the induced absorption recovery is observed by illumination with visible and IR light. This effect is observed for the first time in a Ce-doped scintillation material. It indicates, that radiation induced absorption in DSB: Ce scintillation material can be retained at the acceptable level by stimulation with light in a strong irradiation environment of collider experiments.
Performance of the prototype of the electromagnetic calorimeter for PANDA Kavatsyuk, M.; Bremer, D.; Dormenev, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2011, Letnik:
648, Številka:
1
Journal Article
Recenzirano
The PANDA collaboration at FAIR, Germany, will employ antiproton annihilations to investigate yet undiscovered charm-meson states and glueballs. The aim is to study QCD phenomena in the ...non-perturbative regime and to unravel the origin of hadronic masses. A multi-purpose detector for tracking, calorimetry and particle identification is presently being developed to run at high luminosities providing up to 2×107 interactions/s. One of the crucial components of the PANDA spectrometer is the Electromagnetic Calorimeter, composed of cooled PbWO4 crystals. This paper describes construction and performance of a fully functioning prototype of this calorimeter. The performance was determined from measurements exploiting cosmic muons and high-energy tagged photons from the MAMI-C electron accelerator. The response measurements were carried out using sampling ADCs and, for comparison, charge-integrating ADCs. The achieved results validate the usage of sampling ADCs with a moderate sampling frequency, provide the energy resolution as foreseen in the Technical Design Report of the full calorimeter, and secure event correlation by achieving a good timing resolution through digital analysis of the sampled signals.
The scintillator gadolinium aluminium gallium garnet (Gd3Al2Ga3O12, GAGG) was found to be an excellent material for application in non-homogeneous detecting cells for future calorimeters, operating ...in a harsh irradiation environment. GAGG, activated by cerium ions, can be used to detect γ-quanta and to absorb efficiently neutrons in a wide energy range. The capture of neutrons is accompanied by the emission of relatively soft γ-quanta which can be ignored at calorimetric measurements above 10 MeV. These findings create prospects to construct compact detectors for different purposes, from particle physics to industry.
Simple Test and Modeling of RFID Tag Backscatter Kuester, D. G.; Novotny, D. R.; Guerrieri, J. R. ...
IEEE transactions on microwave theory and techniques,
07/2012, Letnik:
60, Številka:
7
Journal Article
Recenzirano
We consider here worst-case analysis of backscatter from passive radio frequency identification (RFID) tags. The basis is a figure of merit "B" to relate link power at reader ports to tag circuit ...parameters. A minimum bound for received monostatic backscatter can be determined by inspection from measured B. The bound is general for narrowband signals in any causal linear propagation. For an assembled tag, this minimum varies only with reader transmit power, tag antenna tuning, and chip power sensitivity of different commands. To validate this model, we propose a backscatter calibration device to enable measurements with estimated 0.5 dB uncertainty. We then demonstrate how the minimum bound can inform reader sensitivity specification to help ensure reliable inventory performance.
Background On-demand relaparotomy has been associated with a slightly decreased mortality compared to planned relaparotomy in the surgical treatment of secondary peritonitis. On-demand relaparotomy ...must be performed without delay to detect progressing sepsis early, before the onset of multiorgan failure. The aim of the study was to evaluate procalcitonin (PCT) as a parameter for early detection of progressing sepsis after operative treatment of the infective source. Methods In 104 consecutive patients with secondary peritonitis, PCT serum levels were monitored on postoperative days 1 and 2 after initial operative elimination of the septic focus. The PCT ratio between postoperative days 1 and 2 was calculated and correlated to the success of the initial intervention. The latter was considered inadequate if relaparotomies were necessary to eliminate the intraabdominal infection. Results Using classification and regression tree analysis, a cutoff could be calculated at 1.03 for the PCT ratio of postoperative day 1 to day 2. Lesser values indicated unsuccessful elimination of the septic source, whereas values above 1.03 represented successful operative treatment of the septic focus. Unsuccessful treatment of the septic process could be detected with a specificity of 63% and a sensitivity of 95%. Conclusion The PCT ratio appears to be a valuable aid in deciding if further relaparotomies are necessary after initial operative treatment of an intraabdominal septic focus.
It is still a matter of debate whether subtotal esophagectomy via a right thoracoabdominal approach (RTA) or extended gastrectomy using a transhiatal-abdominal approach (TH) is the favorable ...technique in the treatment of Siewert type II esophago-gastric junction adenocarcinoma (EJA).
Patients undergoing RTA or TH for EJA at our institution between 2000 and 2013 were extracted from a prospective database. Of 270 patients 91 (33.7%) underwent RTA and 179 (66.3%) were treated by TH.
Differences in baseline characteristics, 30d mortality and complications were investigated using the χ2-test or exact testing. Survival analysis was performed using the Kaplan-Meier method and log rank testing. Median survival and hazard ratios were calculated and multivariable analysis of predictors was performed using a Cox model. Confounders were balanced using propensity score matching (PSM).
No significant difference between the two procedures was detected regarding overall-survival (OS) and disease-free survival (DFS). 30d mortality rates were 1.1% in the RTA group and 4.5% in the TH group (p = 0.134). Morbidity was 34.1% in the RTA and 24.6% in the TH group (p = 0.006). Cox regression analysis identified age, ASA class and UICC stage as independent prognostic factors for OS. After PSM survival curves (OS + PFS) showed no significant difference.
The present study could not detect a difference between RTA and TH from the oncologic point of view; RTA was not associated with higher 30d mortality. RTA for Siewert Type II EJA is justified whenever the oral tumor margin cannot be safely reached via a transhiatal approach.
SYNOPSIS: Outcomes of transthoracic esophagectomy or extended gastrectomy through a transhiatal-abdominal approach for adenocarcinoma of the cardia were compared. Both procedures are oncologically equivalent. The indication for abdominothoracic approach is dictated by the luminal extension of the tumor into the distal esophagus.
The well-established technology of electromagnetic calorimetry using Lead Tungstate crystals has recently seen an upheaval, with the closure of one of the most experienced large-scale suppliers of ...such crystals, the Bogoroditsk Technical Chemical Plant (BTCP), which was instrumental in the development of mass production procedures for PWO-II, the current benchmark for this scintillator. Obtaining alternative supplies of Lead Tungstate crystals matching the demanding specifications of contemporary calorimeter devices now presents a significant challenge to detector research and development programmes.
In this paper we describe a programme of assessment carried out for the selection, based upon the performance under irradiation, of Lead Tungstate crystals for use in the Forward Tagger device, part of the CLAS12 detector in Hall B at Jefferson Lab. The crystals tested were acquired from SICCAS, the Shanghai Institute of Ceramics, Chinese Academy of Sciences. The tests performed are intended to maximise the performance of the detector within the practicalities of the crystal manufacturing process.
Results of light transmission, before and after gamma ray irradiation, are presented and used to calculate dk, the induced radiation absorption coefficient, at 420nm, the peak of the Lead Tungstate emission spectrum. Results for the SICCAS crystals are compared with identical measurements carried out on Bogoroditsk samples, which were acquired for the Forward Tagger development program before the closure of the facility.
Also presented are a series of tests performed to determine the feasibility of recovering radiation damage to the crystals using illumination from an LED, with such illumination available in the Forward Tagger from a light monitoring system integral to the detector.
In the last forty years, application of crystalline materials in ionizing radiation detectors has played a crucial role in the discovery of matter properties and promoted a continuous progress in the ...detecting technique. Further concepts of the detectors at HEP experiments will require an unique combination of the material features, particularly in case of collider experiments. Crucially important becomes a minimal level of radiation damage effects under the electromagnetic part of ionizing radiation and energetic hadrons as well: low deterioration of the optical transmission, low level of afterglow and low level of radioluminescence due to radio-nuclides being generated due to secondary nuclear reactions in the detector material itself. A systematic study of the radiation hardness of inorganic optical and scintillation materials have been performed. We concluded that both oxide and fluoride crystals which consist of atoms with atomic number less than 60 will be reasonably survivable in the irradiation environment of future experiments at colliders. In this study we focused on the study of cheap, capable for a mass production glass (BaO*2SiO2) and DSB: Ce glass ceramics obtained from this glass. We also made this glass more heavy by admixing gadolinium oxide into the matrix. Glass with Gd3+ admixture possesses two times larger light yield than pure (BaO*2SiO2) glass and glass ceramics. Both types of the materials were produced as fibre and blocks of larger volume.
Validation of a U.S.-derived nomogram for individual prediction of disease-specific gastric cancer survival at a European institution.
One major issue of modern cancer treatment is the ...individualization of therapy. For gastric cancer, Kattan et al, at Memorial Sloan-Kettering Cancer Center, New York, NY, developed a nomogram, allowing to predict individual patient risk of tumor-related death after R0 resection from basic patient-related variables. The validity of the nomogram has not yet been shown in patients from other institutions. The accuracy of the nomogram when applied to patients after having undergone R0 gastric cancer resection at a European high-volume center was investigated.
Clinical data from patients who underwent R0 gastric cancer resection at Klinikum rechts der Isar, Technical University of Munich, Germany and fitted the respective derivation criteria were used for external validation (n = 862). Nomogram predictions for 60- and 108-month disease-specific survival were calculated for each patient and compared with actual survival. The concordance index was used as an accuracy measure.
The bootstrap-corrected concordance index was 0.77 and was superior when compared with the predictive ability of International Union Against Cancer tumor stage (P < 0.008). Nomogram calibration was excellent for 60-month disease-specific survival. Nomogram predictions showed the trend to underestimate survival in stage II/III disease of the MRI patients.
The use of the nomogram created by Kattan et al is not only confined to the institution where it was created, but it can be adopted by other institutions with similar surgical strategies.
Because neural invasion (NI) is still inconsistently reported and not well characterized within gastrointestinal malignancies (GIMs), our aim was to determine the exact prevalence and severity of NI ...and to elucidate the true impact of NI on patient's prognosis.
The union internationale contre le cancer (UICC) recently added NI as a novel parameter in the current TNM classification. However, there are only a few existing studies with specific focus on NI, so that the distinct role of NI in GIMs is still uncertain.
NI was characterized in approximately 16,000 hematoxylin and eosin tissue sections from 2050 patients with adenocarcinoma of the esophagogastric junction (AEG)-I-III, squamous cell carcinoma (SCC) of the esophagus, gastric cancer (GC), colon cancer (CC), rectal cancer (RC), cholangiocellular cancer (CCC), hepatocellular cancer (HCC), and pancreatic cancer (PC). NI prevalence and severity was determined and related to patient's prognosis and survival.
NI prevalence largely varied between HCC/6%, CC/28%, RC/34%, AEG-I/36% and AEG-II/36%, SCC/37%, GC/38%, CCC/58%, and AEG-III/65% to PC/100%. NI severity score was uppermost in PC (24.9±1.9) and lowest in AEG-I (0.8±0.3). Multivariable analyses including age, sex, TNM stage, and grading revealed that the prevalence of NI was significantly associated with diminished survival in AEG-II/III, GC, and RC. However, increasing NI severity impaired survival in AEG-II/III and PC only.
NI prevalence and NI severity strongly vary within GIMs. Determination of NI severity in GIMs is a more precise tool than solely recording the presence of NI and revealed dismal prognostic impact on patients with AEG-II/III and PC. Evidently, NI is not a concomitant side feature in GIMs and, therefore, deserves special attention for improved patient stratification and individualized therapy after surgery.
PDF
