We have developed a new type of particle identification device, called an aerogel ring imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov ...radiators. For detection of Cherenkov photons, hybrid avalanche photo-detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron and
$\gamma $
-ray radiation that exceeds the levels expected in the 10-year Belle II operation. In order to confirm the basic performance of the ARICH counter system, we carried out a beam test at the using a prototype of the ARICH counter with six HAPD modules. The results are in agreement with our expectations and confirm the suitability of the ARICH counter for the Belle II experiment. Based on the in-beam performance of the device, we expect that the identification efficiency at
$3.5\,{\rm GeV}/c$
is 97.4% and 4.9% for pions and kaons, respectively. This paper summarizes the development of the HAPD for the ARICH and the evaluation of the performance of the prototype ARICH counter built with the final design components.
Cetuximab-containing treatments for metastatic colorectal cancer have been shown to have higher overall response rates and longer progression-free and overall survival than other systemic therapies. ...Cetuximab-related manifestations, including severe skin toxicity and early tumor shrinkage, have been shown to be predictors of response to cetuximab. We hypothesized that early skin toxicity is a predictor of response and better outcomes in patients with advanced colorectal carcinoma. We retrospectively evaluated 62 patients with colorectal adenocarcinoma who had unresectable tumors and were treated with cetuximab in our institution. Skin toxicity grade was evaluated on each treatment day. Tumor size was evaluated using computed tomography prior to treatment and 4–8 weeks after the start of treatment with cetuximab.Patients with early tumor shrinkage after starting treatment with cetuximab had a significantly higher overall response rate (
P
= 0.0001). Patients with early skin toxicity showed significantly longer overall survival (
P
= 0.0305), and patients with higher skin toxicity grades had longer progression-free survival (
P
= 0.0168).We have shown that early tumor shrinkage, early onset of skin toxicity, and high skin toxicity grade are predictors of treatment efficacy and/or outcome in patients with advanced colorectal carcinoma treated with cetuximab.
A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1–
4
GeV
/
c
pion beams at KEK. ...Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. In the opposite case of decreasing refractive index, one may obtain well separated rings. In the former combination an approximately 40% increase in photon yield is accompanied with just a minor degradation in single photon angular resolution. The impact of this improvement on the
π
/
K
separation at the upgraded Belle detector is discussed.
Aerogel RICH for forward PID at Belle II Pestotnik, R.; Adachi, I.; Hara, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
For the Belle II spectrometer we are preparing a proximity focusing RICH with aerogel as the radiator. It will be positioned in the forward direction of the spectrometer in the small space between ...the drift chamber and the electromagnetic calorimeter inside a strong magnetic field of 1.5T. The Hybrid Avalanche Photo Diode used as a photo sensor, is able to detect single photons with a high efficiency, can operate in the magnetic field and is resistant to the expected neutron and gamma fluxes in the detector. By detecting more than 11 photons per incident 4GeV/c pion, with 15mrad single photon Cherenkov angle resolution, the designed aerogel RICH should enable an efficient separation of kaons from pions in the wide range of particle momenta from 0.5GeV/c up to 4GeV/c.
Imaging characteristics of glass capillary plate gas detector Tokanai, F.; Sugiyama, H.; Sumiyoshi, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
A glass capillary plate (CP) gas detector with gas mixtures of He, Ne, Ar, and Xe has been successfully operated as a visible and near-infrared (NIR) scintillation proportional counter. Gas gains of ...up to 104 can be achieved using these gas mixtures. The scintillation light emitted during the generation of electron avalanches can be observed using a photomultiplier tube (PMT) and a compact optical imaging system that consists of a CP gas detector and a cooled CCD camera coupled to lens optics. Using this optical imaging system, clearer X-ray images have been obtained with the above gas mixtures. The dependence of the imaging quality on the pressure in the range 0.25–1atm was also investigated for the Ar (90%)+CF4 (10%) gas mixture. The successful operations using these gas mixtures have allowed us to realize a novel imaging device with a CP gas detector for gaseous PMTs sensitive to visible light.
We have tested a new gaseous detector structure based on a tandem of two parts, the first one is a single MCP plate
1
1
In this paper we have decided to use the MCP name throughout, both for vacuum ...and gaseous applications.
(sometimes called the Microchannel plate or Capillary plate), and the second one is a Micromegas with pad readout. The new detector responds very well to a single electron signal, both in Helium- and Argon-based gases, and it can reach a very large gain. We also measure the ion backflow. Our overall aim is to couple the proposed electrode structure to a Bialkali photocathode. The main advantage of this avenue of research is that such a detector would operate easily in a very large magnetic field, and it could achieve excellent position resolution and large pixelization, compared to existing vacuum-based MCP-PMT detectors, and that the glass-based MCP structure is compatible with the Bialkali photocathode. We propose a new concept of angled MCP holes for the gaseous detectors to reduce the ion backflow towards the photocathode material.
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