Previous studies show remarkable differences in the simulation of electron depth dose profiles of ruthenium eye plaques. We examined the influence of the scoring and simulation geometry, the source ...spectrum and the multiple scattering algorithm on the depth dose profile using GEANT4. The simulated absolute dose deposition agrees with absolute dose data from the manufacturer within the measurement uncertainty. Variations in the simulation geometry as well as the source spectrum have only a small influence on the depth dose profiles. However, the multiple scattering algorithms have the largest influence on the depth dose profiles. They deposit up to 20% less dose compared to the single scattering implementation. We recommend researchers who are interested in simulating low- to medium-energy electrons to examine their simulation under the influence of different multiple scattering settings. Since the simulation and scoring geometry as well as the exact physics settings are best described by the source code of the application, we made the code publicly available.
The LHCb Outer Tracker is a gaseous detector covering an area of 5×6m2 with 12 double layers of straw tubes. The performance of the detector is presented based on data of the LHC Run 2 running period ...from 2015 and 2016. Occupancies and operational experience for data collected in pp, pPb and PbPb collisions are described. An updated study of the ageing effects is presented showing no signs of gain deterioration or other radiation damage effects. In addition several improvements with respect to LHC Run 1 data taking are introduced. A novel real-time calibration of the time-alignment of the detector and the alignment of the single monolayers composing detector modules are presented, improving the drift-time and position resolution of the detector by 20%. Finally, a potential use of the improved resolution for the timing of charged tracks is described, showing the possibility to identify low-momentum hadrons with their time-of-flight.
The LHCb Outer Tracker is a gaseous detector covering an area of 5 x 6 m super(2) with 12 double layers of straw tubes. The detector with its services are described together with the commissioning ...and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 mu m. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.
An xyz-measuring table with a modular design has been developed for the determination of the individual 3D dose rate distributions of different brachytherapy sources requiring a high spatial ...resolution and reproducibility. The instrumental setup consists of a plastic scintillator detector system and the xyz-measuring table for guiding the detector across the radioactive sources. For this purpose, a micro positioning system with piezo inertial drives is chosen, providing a step width of 450 nm. To ensure a high reproducibility and accuracy better than 1 μm, an exposed linear encoder controls the positioning. The successful operation of the xyz-measuring table is exemplarily shown by measurements of dose profiles of two brachytherapy sources, an ophthalmic plaque and a radioactive seed. The setup allows a fully automated quality assurance of ophthalmic plaques and radioactive seeds under clinical conditions and can be extended to other (brachytherapy) sources of similar dimensions.
Radiation hardness of the LHCb Outer Tracker van Eijk, D.; Bachmann, S.; Bauer, Th ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2012, Letnik:
685
Journal Article
Recenzirano
Odprti dostop
This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to ...gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3fb−1 of integrated luminosity corresponding to an integrated charge of 0.055C/cm in the hottest spot of the detector.
Tau physics at future machines Spaan, B.
Nuclear physics. Section B, Proceedings supplement,
05/1997, Letnik:
55, Številka:
3
Journal Article
Recenzirano
The prospects on Tau physics at future machines will be discussed, with future machines under consideration are B-factories and a τ/charm factory. Based on the experiences maded at existing ...experiments, the focus of this talk will be the issue of precision measurements and the need for the reduction of systematic errors.
The straw tube technology for the LHCb outer tracking system Bachmann, S.; Bagaturia, I.; Deppe, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2004, Letnik:
535, Številka:
1
Journal Article
Recenzirano
Odprti dostop
For the outer tracking system of the LHCb spectrometer 53.760 straws of 2.5
m length will be used. They are arranged in detector modules of 5
m length and 0.34
m width. The envisaged spatial ...resolution over the entire active area is 200
μ
m resulting in stringent requirements on the accuracy for the module construction.
In this paper we discuss the optimisation of the straws, design and construction of detector modules. The long-term operation properties of straws in two different counting gases, Ar/CO
2
(70/30) and Ar/CO
2
/CF
4
(75/10/15), are compared.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II, we have searched for the real and imaginary part of the electric dipole formfactor
d
τ
of the
τ lepton in the production of
τ pairs at
q
...2=100
GeV
2
. This is the first direct measurement of this
CP
violating formfactor. We applied the method of optimised observables which takes into account all available information on the observed
τ decay products. No evidence for
CP
violation was found, and we derive the following results:
Re(d
τ)=(1.6±1.9)·10
−16
e
cm
and
Im(d
τ)=(−0.2±0.8)·10
−16
e
cm
, where statistical and systematic errors have been combined.
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