Light Yield and Light Collection Uniformity

In the field of scintillators, high scintillation and light production performance require high-quality crystals. Although the composition and structure of crystals are fundamental in this direction, their ultimate optical performance is strongly dependent on the surface finishing treatment. This paper compares two surface finishing methods in terms of the final structural condition of the surface and the relative light yield performances. The first polishing method is the conventional “Mechanical Diamond Polishing” (MDP) technique. The second polishing technique is a method applied in the electronics industry which is envisaged for finishing the surface treatment of scintillator crystals. This method, named “Chemical Mechanical Polishing” (CMP), is efficient in terms of the cost and material removal rate and is expected to produce low perturbed surface layers, with a possible improvement of the internal reflectivity and, in turn, the light collection efficiency. The two methods have been applied to a lead tungstate PbWO4 (PWO) single crystal due to the wide diffusion of this material in high energy physics (CERN, PANDA project) and diagnostic medical applications. The light yield (LY) values of both the MDP and CMP treated crystals were measured by using the facilities at CERN while their surface structure was investigated by Scanning Electron Microscopy (SEM) and Grazing Incidence X-ray Diffraction (GID). We present here the corresponding optical results and their relationship with the processing conditions and subsurface structure.

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Optimization of a light collection in the Shashlyk-type electromagnetic calorimeter with projective geometry for the NICA/MPD experiment.

EPJ Web of Conferences ◽

10.1051/epjconf/201922202007 ◽

2019 ◽

Vol 222 ◽

pp. 02007 ◽

Cited By ~ 3

Author(s):

Artur Durum ◽

Gennadiy Britvich ◽

Sergey Chernichenko ◽

Alexei Denisov ◽

Mikhail Kostin ◽

...

Keyword(s):

Projective Geometry ◽

Tracking System ◽

Light Yield ◽

Heavy Ion ◽

Electromagnetic Calorimeter ◽

Light Collection ◽

Neutral Particles ◽

Ion Collisions ◽

Under Construction ◽

Nica Collider

The MPD spectrometer at the NICA collider complex is currently under construction in Dubna. The main goal of the experiment is to obtain fundamental knowledge about the properties of hot and dense baryonic matter formed in heavy-ion collisions in the energy range of (4-11) A*GeV. Crucial detector of the MPD experiment is a large-sized barrel electromagnetic calorimeter (ECal), which (together with the tracking system) will provide unique opportunities for the measurement and identification of a wide variety of charged and neutral particles carrying information about early stages of the interactions. Important tasks related to the construction of the Shashlyk-type MPD ECal are the development, production and study of the calorimeter modules with projective geometry. To improve performance of ECal, the light collection in the modules should be optimized. We present the methods and technologies developed to increase the light yield with different types and configurations of reflectors on the end of wavelengths shifting fibers. Expected characteristics of the calorimeter in detection of photons and electrons are presented and discussed

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Prospects for High Energy Resolution Gamma Ray Spectroscopy with Europium-Doped Strontium Iodide

MRS Proceedings ◽

10.1557/proc-1164-l11-04 ◽

2009 ◽

Vol 1164 ◽

Cited By ~ 5

Author(s):

Nerine Cherepy ◽

S A. Payne ◽

Rastgo Hawrami ◽

A Burger ◽

Lynn Boatner ◽

...

Keyword(s):

Energy Resolution ◽

Gamma Ray ◽

Light Yield ◽

Crystal Form ◽

High Energy ◽

High Energy Resolution ◽

Light Collection ◽

Chemical Homogeneity ◽

Crystal Structural ◽

Crystal Volume

AbstractEuropium-doped strontium iodide scintillators offer a light yield exceeding 100,000 photons/MeV and excellent light yield proportionality, while at the same time, SrI2 is readily grown in single crystal form. Thus far, our collaboration has demonstrated an energy resolution with strontium iodide of 2.6% at 662 keV and 7.6% at 60 keV, and we have grown single crystals surpassing 30 cm3 in size (with lower resolution). Our analysis indicates that SrI2(Eu) has the potential to offer 2% energy resolution at 662 keV with optimized material, optics, and read-out. In particular, improvements in feedstock purity may result in crystal structural and chemical homogeneity, leading to improved light yield uniformity throughout the crystal volume, and consequently, better energy resolution. Uniform, efficient light collection and detection, is also required to achieve the best energy resolution with a SrI2(Eu) scintillator device.

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Counting neutrons with a commercial S-CMOS camera

EPJ Web of Conferences ◽

10.1051/epjconf/201817001018 ◽

2018 ◽

Vol 170 ◽

pp. 01018 ◽

Cited By ~ 1

Author(s):

Van Esch Patrick ◽

Mutti Paolo ◽

Ruiz-Martinez Emilio ◽

Abad Garcia Estefania ◽

Mosconi Marita ◽

...

Keyword(s):

Image Processing ◽

Data Flow ◽

Light Yield ◽

Image Data ◽

Scientific Instrument ◽

Light Collection ◽

Imaging Data ◽

Cmos Camera ◽

Main Challenge ◽

On Line

It is possible to detect individual flashes from thermal neutron impacts in a ZnS scintillator using a CMOS camera looking at the scintillator screen, and off line image processing. Some preliminary results indicated that the efficiency of recognition could be improved by optimizing the light collection and the image processing. We will report on this ongoing work which is a result from the collaboration between ESS Bilbao and the ILL. The main progress to be reported is situated on the level of the on-line treatment of the imaging data. If this technology is to work on a genuine scientific instrument, it is necessary that all the processing happens on line, to avoid the accumulation of large amounts of image data to be analyzed off line. An FPGA-based real-time full-deca mode VME-compatible CameraLink board has been developed at the SCI of the ILL, which is able to manage the data flow from the camera and convert it in a reasonable “neutron impact” data flow like from a usual neutron counting detector. The main challenge of the endeavor is the optical light collection from the scintillator. While the light yield of a ZnS scintillator is a priori rather important, the amount of light collected with a photographic objective is small. Different scintillators and different light collection techniques have been experimented with and results will be shown for different setups improving upon the light recuperation on the camera sensor. Improvements on the algorithm side will also be presented. The algorithms have to be at the same time efficient in their recognition of neutron signals, in their rejection of noise signals (internal and external to the camera) but also have to be simple enough to be easily implemented in the FPGA. The path from the idea of detecting individual neutron impacts with a CMOS camera to a practical working instrument detector is challenging, and in this paper we will give an overview of the part of the road that has already been walked.

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Light collection simulation when determining light yield of single crystal and polycrystalline organic scintillators

Functional materials ◽

10.15407/fm22.03.408 ◽

2015 ◽

Vol 22 (3) ◽

pp. 408-415 ◽

Cited By ~ 3

Author(s):

T.E. Gorbacheva ◽

◽

Keyword(s):

Single Crystal ◽

Light Yield ◽

Light Collection ◽

Organic Scintillators

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Corrigendum to ‘Light yield nonproportionality, intrinsic resolution and α/γ ratio of oxide single crystal scintillators’.[Radiation Measurements 125 (2019) 73–77]

Radiation Measurements ◽

10.1016/j.radmeas.2020.106510 ◽

2021 ◽

Vol 140 ◽

pp. 106510

Author(s):

Krittiya Sreebunpeng ◽

Nattasuda Yawai ◽

Warut Chewpraditkul ◽

Ongsa Sakthong ◽

Weerapong Chewpraditkul

Keyword(s):

Single Crystal ◽

Light Yield ◽

Intrinsic Resolution ◽

Radiation Measurements

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Simulations of light collection in long tapered CsI(Tl) scintillators using real crystal surface data and comparisons to measurement

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment ◽

10.1016/j.nima.2021.165302 ◽

2021 ◽

pp. 165302

Author(s):

A. Knyazev ◽

J. Park ◽

P. Golubev ◽

J. Cederkäll ◽

H. Alvarez-Pol ◽

...

Keyword(s):

Crystal Surface ◽

Light Collection ◽

Real Crystal ◽

Surface Data

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Novel Cs2HfCl6 Crystal Scintillator: Recent Progress and Perspectives

Physics ◽

10.3390/physics3020023 ◽

2021 ◽

Vol 3 (2) ◽

pp. 320-351

Author(s):

Serge Nagorny

Keyword(s):

Recent Progress ◽

Raw Materials ◽

Light Output ◽

Light Yield ◽

Thermal Conditions ◽

Pulse Shape Discrimination ◽

Main Element ◽

High Quality ◽

Crystal Sample ◽

Discrimination Ability

Recent progress in Cs2HfCl6 (CHC) crystal production achieved within the last five years is presented. Various aspects have been analyzed, including the chemical purity of raw materials, purification methods, optimization of the growth and thermal conditions, crystal characterization, defect structure, and internal radioactive background. Large volume, crack-free, and high quality CHC crystals with an ultimate scintillating performance were produced as a result of such extensive research and development (R & D) program. For example, the CHC crystal sample with dimensions ∅23 × 30 mm3 demonstrates energy resolution of 3.2% FWHM at 662 keV, the relative light output at the level of 30,000 ph/MeV and excellent linearity down to 20 keV. Additionally, this material exhibits excellent pulse shape discrimination ability and low internal background of less than 1 Bq/kg. Furthermore, attempts to produce a high quality CHC crystal resulted in research on this material optimization by constitution of either alkali ions (Cs to Tl), or main element (Hf to Zr), or halogen ions (Cl to Br, I, or their mixture in different ratio), as well as doping with various active ions (Te4+, Ce3+, Eu3+, etc.). This leads to a range of new established scintillating materials, such as Tl2HfCl6, Tl2ZrCl6, Cs2HfCl4Br2, Cs2HfCl3Br3, Cs2ZrCl6, and Cs2HfI6. To exploit the whole potential of these compounds, detailed studies of the material’s fundamental properties, and understanding of the variety of the luminescence mechanisms are required. This will help to understand the origin of the high light yield and possible paths to further extend it. Perspectives of CHC crystals and related materials as detectors for rare nuclear processes are also discussed.

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