Data underlying the publication: A novel method to assess crosstalk in single-grain luminescence detection

For more information please see the README file in the "Data-4TU" folder which contains all scripts, data, and a manual.<br># Paper abstract <br> Luminescence imaging with an EMCCD camera is an innovative approach to single-grain luminescence detection. In theory, it allows for the random placement of grains on a disc, but in practice, attributing photons to specific grains remains unachievable. Currently, single-grain discs with fixed grain placement are primarily used, though these are still susceptible to crosstalk, e.g. overlapping of luminescence signals from adjacent grains. A standardized method for identifying, correcting, or eliminating crosstalk is not yet available. In this paper, we introduce Moran’s I, a measure of spatial autocorrelation, as a novel method for assessing crosstalk in single-grain luminescence detection. Using simulations with induced crosstalk, we demonstrate that Moran’s I can effectively detect crosstalk when interpreted within the context of its pseudo-p value. These results are corroborated by those obtained on a measured luminescence dataset for which crosstalk is deliberately enhanced by increasing the region of interest (ROI) selected for luminescence signal integration. These results on simulated and measured data show that Moran’s I can be used to select optimal ROI size to enhance signals whilst limiting crosstalk. Finally, we examined the effect of modelled crosstalk on three types of equivalent-dose distributions, finding that normal distributions are unaffected by crosstalk, whereas bimodal distributions became mixed, and the shape of skewed distributions alters. These results have implications for ROI selection for well-bleached, mixed and heterogeneously bleached sediments. <br># Measurements <br>+ Luminescence measurementsAll measurements were made on a Risø TL/ OSL DA-20 reader with an automated detection and stimulation head (DASH) and an EMCCD camera (Kook et al., 2015). The system is fitted with a calibrated 90Sr/90Y beta source which delivers a dose rate of approximately 0.0954 Gy/s to grains on a single-grain disc. The sample was stimulated with IR LEDs at 850 nm and a blue package filter (BG-3 (3.0 mm) + BG-39 (4.0 mm)) was used to target the 410 nm K-feldspar emission peak. We adopted a multi-elevated-temperature (MET) pIRIR measurement protocol with IRSL read-outs at 50, 110, 170, and 230 ◦C (Table 1) (Li &amp; Li, 2011). We measured three single-grain discs per sample, which makes a total of 45 discs. We chose to only study crosstalk effects on the IRSL-50 signal for the net natural test dose (8.1 Gy) response (Table 1, step 12 manuscript), which carries information about the luminescence sensitivity of the grains. The net natural test dose response (Net_TnTx ± Net_TnTx.Error) was alculated by subtracting the background test dose response (TnTx.BG) integrated over channel 210 up to 260 (20 s) from the initial test dose response (TnTx) integrated over channel 11 up to 31 (8 s) to create a single-grain brightness distribution (Wallinga, 2002). The measured data were analyzed with Risø Viewer+ software and extracted for nine different ROI sizes: 300, 450, 600, 750, 900, 1050, 1200, 1350 and 1500 μm, i.e. ranging from the hole dimension (300 μm) up to overlapping with the adjacent grain hole (1500 μm). The spacing between grain positions on the single-grain disc is 600 μm. We assume that grains of varying sensitivity are randomly distributed over the single-grain disc grid. Subsequent analyses were performed within the R environment for statistical computing. <br>Please visit the Netherlands Centre for Luminescence dating (NCL) database for more information on the sample background at: https://www.lumid.nl/.  On the website go to the 'projects' tab and search for NCL-code 1321.<br>+ Measurement protocols and data formats The measurement protocols were written in Riso's sequence editor software (.seq files). All Riso software is downloadable at: https://www.fysik.dtu.dk/english/research/radphys/research/radiation-instruments/tl_osl_reader/software. The raw data is stored in a Riso .binx file which can be opened in Riso's analyst software environmen. We analyzed the raw data in Riso's Viewer+ to extract the luminescence signal for several Region Of Interests (ROIs). <br>+ Processing and analysis scripts in R All processing of data (modifications, calculations, etc) and analysis of data was performed in R. All  scripts are commented. Per measurement type an R script was written.  <br>+ Figures and tables All figures and tables were created through R and/ or Adobe Illustrator. Refer to the R scripts for detailed information within the script.

如需更多信息，请查阅"Data-4TU"文件夹中的README文件，该文件夹包含所有脚本、数据集与使用手册。
# 论文摘要
采用电子倍增电荷耦合器件（EMCCD）相机进行光释光成像，是单颗粒光释光检测的创新方案。理论上，该方案可实现颗粒在圆盘上的随机排布，但实际应用中，仍无法将光子信号归因至特定颗粒。目前主流方案为使用颗粒位置固定的单颗粒圆盘，但此类圆盘仍易出现串扰问题，例如相邻颗粒的光释光信号发生重叠。目前尚无标准化方法可用于识别、校正或消除此类串扰。本文引入空间自相关度量指标莫兰指数（Moran’s I），作为单颗粒光释光检测中串扰评估的新方法。通过引入人为串扰的仿真实验，本文证明，结合伪p值进行解读时，莫兰指数可有效检测串扰信号。通过对光释光实测数据集开展分析（该数据集通过增大光释光信号积分的感兴趣区域（ROI），刻意增强了串扰程度），进一步验证了上述结论。仿真与实测数据的分析结果均表明，莫兰指数可用于筛选最优ROI尺寸，在提升信号强度的同时限制串扰。最后，本文探究了模拟串扰对三类等效剂量分布的影响，发现正态分布不受串扰影响，而双峰分布会出现混合现象，偏态分布的形态则会发生改变。上述结论可为纯净漂白、混合及非均匀漂白沉积物的ROI选取提供参考。
# 测量方案
+ 光释光测量
所有测量均在搭载自动检测与激发头（DASH）与电子倍增电荷耦合器件（EMCCD）相机的Risø TL/OSL DA-20型热释光/光释光测年仪上完成（Kook等，2015）。该系统配备校准后的锶90/钇90β放射源，可向单颗粒圆盘上的颗粒提供约0.0954 Gy/s的剂量率。实验采用850 nm红外发光二极管（IR LEDs）激发样品，并搭配蓝色组合滤光片（BG-3 (3.0 mm) + BG-39 (4.0 mm)）以精准采集410 nm处的钾长石发射峰信号。本研究采用多升温模式（MET）下的后红外红外激发光释光（pIRIR）测量方案，分别在50、110、170与230 ℃下进行红外释光（IRSL）读数（见表1）（Li & Li，2011）。每个样品设置3个单颗粒圆盘，总计45个圆盘。本研究仅针对净天然测试剂量（8.1 Gy）响应下的IRSL-50信号开展串扰效应分析（见表1，手稿步骤12），该信号可反映颗粒的光释光灵敏度。净天然测试剂量响应（Net_TnTx ± Net_TnTx.Error）通过积分通道11至31（时长8 s）的初始测试剂量响应（TnTx），减去积分通道210至260（时长20 s）的背景测试剂量响应（TnTx.BG）计算得到，以此构建单颗粒亮度分布（Wallinga，2002）。采用Risø Viewer+软件对实测数据进行分析，并提取9种不同尺寸的感兴趣区域（ROI）对应的信号：300、450、600、750、900、1050、1200、1350与1500 μm，覆盖范围从颗粒孔尺寸（300 μm）直至与相邻颗粒孔重叠（1500 μm）。单颗粒圆盘上的颗粒位置间距为600 μm。本研究假设不同灵敏度的颗粒在单颗粒圆盘网格上随机分布。后续数据分析均在R统计计算环境中完成。
如需了解样品背景的更多信息，请访问荷兰光释光测年中心（NCL）数据库：https://www.lumid.nl/。进入网站后点击“projects”标签页，搜索NCL编码1321即可。
+ 测量方案与数据格式
测量方案通过Riso序列编辑软件编写（.seq格式文件）。所有Riso软件均可从以下网址下载：https://www.fysik.dtu.dk/english/research/radphys/research/radiation-instruments/tl_osl_reader/software。原始数据存储于Riso .binx格式文件中，可通过Riso分析软件环境打开。本研究通过Risø Viewer+软件对原始数据进行分析，提取多种感兴趣区域（ROIs）对应的光释光信号。
+ R语言处理与分析脚本
所有数据处理（包括修改、计算等）与数据分析工作均在R语言环境中完成。所有脚本均带有注释，且针对每一类测量方案编写了专属R脚本。
+ 图表与表格
所有图表均通过R语言与/或Adobe Illustrator绘制，详细参数与生成逻辑可查阅对应R脚本。