اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدEnhanced UV light detection using a p-terphenyl wavelength shifter
50
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths below $300,text{nm}$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $300,text{nm}$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $200,text{nm}$ and $400,text{nm}$. The gain factor ranges up to 5.4 $pm$ 0.5 at a wavelength of $215,text{nm}$, with a material load of $110pm10,mutext{g}/text{cm}^2$ ($894,text{nm}$). The wavelength shifter was found to be fully transparent for wavelengths greater than $300,text{nm}$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold Cherenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.
قيم البحث
اقرأ أيضاً
Liquid argon-based scintillation detectors are important for dark matter searches and neutrino physics. Argon scintillation light is in the vacuum ultraviolet region, making it hard to be detected by conventional means. Polyethylene naphthalate (PEN)
, an optically transparent thermoplastic polyester commercially available as large area sheets or rolls, is proposed as an alternative wavelength shifter to the commonly-used tetraphenyl butadiene (TPB). By combining the existing literature data and spectrometer measurements relative to TPB, we conclude that the fluorescence yield and timing of both materials may be very close. The evidence collected suggests that PEN is a suitable replacement for TPB in liquid argon neutrino detectors, and is also a promising candidate for dark matter detectors. Advantages of PEN are discussed in the context of scaling-up existing technologies to the next generation of very large ktonne-scale detectors. Its simplicity has a potential to facilitate such scale-ups, revolutionizing the field.
We present the development of a neutron detector array module made with $textit{para}$-terphenyl, a bright, fast, n/$gamma$ discriminating crystalline organic scintillator. The module is comprised of 2 cm $times$ 2 cm $times$ 2 cm $textit{p}$-terphen
yl crystals that have been optically coupled together to create a $textit{pseudo-bar}$ module. While only relying on two photo detectors, the module is capable of distinguishing interactions between up to eight crystals. Furthermore, the module retains the $textit{p}$-terphenyls pulse shape discrimination (PSD) capability. Together this makes the pseudo-bar module a promising position-sensitive neutron detector. Here we present characteristics of the pseudo-bar module - its timing resolution as well as its pulse shape and position discrimination capabilities, and briefly discuss future plans for utilizing an array of pseudo-bar modules in a useful neutron detector system.
We have constructed a Doppler-shifter-type pulsed ultra-cold neutron (UCN) source at the Materials and Life Science Experiment Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). Very-cold neutrons (VCNs) with 136-$mathrm{m/s}$
velocity in a neutron beam supplied by a pulsed neutron source are decelerated by reflection on a m=10 wide-band multilayer mirror, yielding pulsed UCN. The mirror is fixed to the tip of a 2,000-rpm rotating arm moving with 68-$mathrm{m/s}$ velocity in the same direction as the VCN. The repetition frequency of the pulsed UCN is $8.33~mathrm{Hz}$ and the time width of the pulse at production is $4.4~mathrm{ms}$. In order to increase the UCN flux, a supermirror guide, wide-band monochromatic mirrors, focus guides, and a UCN extraction guide have been newly installed or improved. The $1~mathrm{MW}$-equivalent count rate of the output neutrons with longitudinal wavelengths longer than $58~mathrm{nm}$ is $1.6 times 10^{2}~mathrm{cps}$, while that of the true UCNs is $80~mathrm{cps}$. The spatial density at production is $1.4~mathrm{UCN/cm^{3}}$. This new UCN source enables us to research and develop apparatuses necessary for the investigation of the neutron electric dipole moment (nEDM).
To optimise the design of the light readout in the ArDM 1-ton liquid argon dark matter detector, a range of reflector and WLS coating combinations were investigated in several small setups, where argon scintillation light was generated by radioactive
sources in gas at normal temperature and pressure and shifted into the blue region by tetraphenyl butadiene (TPB). Various thicknesses of TPB were deposited by spraying and vacuum evaporation onto specular 3M{smalltexttrademark}-foil and diffuse Tetratex{smalltextregistered} (TTX) substrates. Light yields of each reflector and TPB coating combination were compared. Reflection coefficients of TPB coated reflectors were independently measured using a spectroradiometer in a wavelength range between 200 and 650 nm. WLS coating on the PMT window was also studied. These measurements were used to define the parameters of the light reflectors of the ArDM experiment. Fifteen large $120times 25$ cm$^2$ TTX sheets were coated and assembled in the detector. Measurements in argon gas are reported providing good evidence of fulfilling the light collection requirements of the experiment.
A SensL MicroFC-SMT-60035 6x6 mm$^2$ silicon photo-multiplier coated with a NOL-1 wavelength shifter have been tested in the liquid xenon to detect the 175-nm scintillation light. For comparison, a Hamamatsu vacuum ultraviolet sensitive MPPC VUV3 3x3
mm$^2$ was tested under the same conditions. The photodetection efficiency of $13.1 pm 2.5$% and $6.0 pm 1.0$%, correspondingly, is obtained.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
