我正在使用教授提供的模板撰写论文，在三个地方我都收到“出现问题---可能是缺少 \item 错误”的错误提示，但我不知道是什么原因造成的。错误发生在枚举部分的第一个 \item、结果和讨论部分调用以及结果子部分调用中。它导致结果和讨论标题与上一节的最后一句话在同一行开始，而不是像应该的那样单独成行。我使用的代码如下：
\documentclass[11pt]{article}
\usepackage{graphicx, epstopdf}
\usepackage[font=small,labelfont=bf,textfont=bf]{caption}
\usepackage{subcaption}
\usepackage{color}
\usepackage{url}
\usepackage{mathtools}
\usepackage{multirow}
\usepackage{cancel}
\usepackage{abstract}
\usepackage{csquotes}
\addtolength{\textwidth}{1in}
\addtolength{\textheight}{1in}
\addtolength{\evensidemargin}{0.5in}
\addtolength{\oddsidemargin}{-0.5in}
\addtolength{\topmargin}{-0.5in}
\usepackage{tocloft}
\usepackage[nottoc,notlot,notlof]{tocbibind}
\renewcommand{\cftsecleader}{\cftdotfill{\cftdotsep}}
\setcounter{secnumdepth}{0}
\newcommand{\HRule}{\rule{\linewidth}{0.35mm}}
\begin{document}
% this points to a separate .tex file for your title
% note: title.tex is formatted to include a blank page for double-sided printing
\input{./title.tex}
% this points to a separate .tex file for your abstract
% note: abstract.tex is formatted to include a blank page for double-sided printing
\input{./abstract.tex}
\tableofcontents
\listoffigures
\listoftables
\pagenumbering{arabic}
\thispagestyle{empty}
\clearpage
\section{Introduction and Theory}
This experiment is expected to demonstrate what role pulse shaping plays in the nuclear detection process. The objective of this experiment was to become familiar with assembling a basic nuclear pulse processing system. As part of this process we needed to observe and describe the different pulses created at each step of the system. It was also necessary to measure pulse shape parameters, explain why each step in the system is necessary, and describe the effect of the system component settings on the pulse shape.
\bigbreak
The need for pulse shaping in nuclear detection is explored. Pulse shaping refers to a series of operations that are performed on a raw pulse from a detector that make it easier to extract the desired information. The raw pulse (or anode pulse) that is created by the detector and Photo-Multiplier Tube (PMT) carries information about the charge collected and the time it took to collect that charge. It is generally easier to work with amplitudes of pulses rather than the areas under them so this anode pulse is passed through a preamplifier (preamp) which integrates the pulse. Then the height of the preamp pulse (which is now given in voltage) is proportional to the energy (charge collected) and the charge collection time is determined by the rise time of this pulse. The rise time of a preamp pulse is very fast in a charge sensitive (fast) preamp so it is necessary to take the derivative of this pulse to obtain a pulse with a wider rise time. An amplifier does this derivation which leads to a signal that has a better shape to determine the timing of the pulse while preserving the energy (charge) information. After these steps the pulse can be used by a multichannel analyzer (MCA) to determine an energy spectrum or by a single channel analyzer (SCA) which turns the pulse into a logic pulse for counting purposes.
\section{Procedure and Methods}
A pulse processing system was assembled according to the block diagram in Figure \ref{fig:sysblock}.
\begin{figure}[h]
\centering
\includegraphics[width=\textwidth]{BlockDiagram.PNG}
\caption{Block Diagram of System Setup}
\label{fig:sysblock}
\flushleft
\end{figure}
\hspace{-30pt} A list of the equipment used is provided below.
\bigskip
\begin{enumerate}
\item Cs-137 source
\item 2-inch-diameter by 2-inch-long sodium iodide scintillator (2x2 NaI) coupled to a 2-inch-diameter 20-stage PMT
\item 14-pin PMT base with integrated preamp
\item nuclear instrument module (NIM) bin
\item high voltage (HV) power supply
\item amplifier
\item SCA
\item counter/timer
\item MCA
\item oscilloscope (scope)
\end{enumerate}
\bigskip
The final setup is shown in Figure \ref{fig:sysrealrot}. The experiment was carried out by connecting the scope to each component and viewing the pulse that was output at each step. The pulses viewed were from the anode of the PMT, preamp, amp (both unipolar and bipolar), and the SCA. The 10\%-90\% rise and 90\%-10\% fall times for these pulses were visually determined from the scope output as well as measured by the scope. The effects of amplifier gain and shaping time-constant, as well as voltage input to the PMT on the pulse shapes were determined. The setting for the components at each of these steps are detailed below. The counting rate was also determined by the counter/timer and three different pulse height spectra (PHS) were obtained with the MCA.
\begin{figure}[h]
\centering
\includegraphics[width=\textwidth]{sysrealrot.jpg}
\caption{Photograph of Pulse Processing System Setup}
\label{fig:sysrealrot}
\flushleft
\end{figure}
When initially setting up the system the source was put near the detector so the count rate was under $5,000 \frac{counts}{s}$. The HV power supply was set to $700 V$, the amplifier gain was set to $20$, the shaping time was set to $30 \mu s$, The SCA lower level division (LLD) was set to $0.2 V$ and the upper level division (ULD) was set to $10V$. The high voltage was adjusted to $600 V$ so the pulses coming from the amplifier had a peak value around $5 V$. The scope was autoset so we could see the pulses coming from the system.
The initial settings are unchanged in the following descriptions unless otherwise noted. When viewing the anode pulses the oscilloscope was initially set with a horizontal scale of $1 \mu s$ per division and a vertical scale of $50 mV$ per division. When viewing the preamp pulses the oscilloscope was initially set with a horizontal scale of $50 \mu s$ per division and a vertical scale of $100 mV$ per division. When viewing the amplifier unipolar pulses the oscilloscope was initially set with a horizontal scale of $5 \mu s$ per division and a vertical scale of $2 mV$ per division. The gain was then increased to 50 and decreased to 10 to observe the changes to the pulse due to amplifier gain. The shaping time was increased to $10 \mu s$ and decreased to $1 \mu s$ to observe the changes in the pulse due to shaping time. When viewing the amplifier bipolar pulses the oscilloscope was initially set with a horizontal scale of $5 \mu s$ per division and a vertical scale of $2 mV$ per division. When viewing the SCA pulses the LLD was initially set to $5 V$. Then the LLD was changed to $0.2 V$ and the ULD was set to $5 V$ to observe how this changed the pulses. To measure the counting rate the signal from the source was measured 10 times for $10 s$ and 10 more times for $40 s$. The source was then removed and the same counts were measured for the background. The background was then subtracted from the source to obtain an average pulse rate. The inital run of the MCA was done with the inital settings of for the experiment. The second spectrum was obtained with the amplifier gain set to 10. The third spectrum was obtained with the amplifier gain set to 20 and the HV supply set to $570 V$.
\bigskip
\section{Results and Discussion}
\bigskip
See the lab report guide for recommendations for your results and discussion section(s).
There are many ways to write and reference equations. One way is shown in Equation~\ref{eq:power}.
\begin{equation}
P = I V = I^2 R
\label{eq:power}
\end{equation}
And another way is shown in Equation~\ref{eq:multi}.
\begin{eqnarray}
P & = & I V \nonumber \\
& = & I^2 R
\label{eq:multi}
\end{eqnarray}
\subsection{Results}
\bigskip
The subsection is how you can break up a section. Note that the sections are listed in the table of contents and the subsections have a slightly different format (regular text, slightly indented).
\begin{figure}[h]
\centering
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{picture}
\caption{Dish 1}
\label{fig:dish1}
\end{subfigure}
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{picture.jpg}
\caption{Dish 2}
\label{fig:dish2}
\end{subfigure}
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{picture.jpg}
\caption{Dish 3}
\label{fig:dish3}
\end{subfigure}
\flushleft
\caption{Multi-figure figure}{This is an example of placing multiple figures together. You can reference sub-figures just like a single figure. As an example, Figure~\ref{fig:dish2} is a reference to the middle figure.}
\label{fig:multi_biscuits}
\end{figure}
\subsection{Discussion}
Placeholder for discussion subsection with an example of a citation. \cite{refMattingly}
\section{Conclusions}
See the lab report for recommendations for your conclusions.
% there are many ways to do references; this is a simple way if you only have a couple
\bibliographystyle{plain}
\begin{thebibliography}{9}
\bibitem{refMattingly}
John Mattingly and Dean J. Mitchell,
\enquote{A framework for the solution of inverse radiation transport problems,}
\emph{Trans. Nucl. Sci}, {\bf 75}(6), November 2010, pp. 3734-3743.
\end{thebibliography}
\end{document}
title.tex 文件：
\begin{titlepage}
\flushleft
{\LARGE\bf Lab 1: Nuclear Pulse Processing Instrumentation}
\noindent\textcolor{red}\HRule \\[0.50cm]
Name: Robert Valdillez \\
Partners: Innocent Tsorxe\\[0.50cm]
Date performed: 10/3/2019 \\
Date due: 10/10/2019\\[0.50cm]
Instructor: Dr. John Mattingly \\
Teaching assistant: Zheng Zhang \\
\clearpage\mbox{}\thispagestyle{empty}\clearpage
\end{titlepage}
以及 abstract.tex 文件：
\flushleft
\section{Abstract}
See the lab report guide for recommendations for your abstract.
\thispagestyle{empty}
\clearpage
\mbox{}
\thispagestyle{empty}
\clearpage
答案1
\flushleft三个环境的末尾都figure出现了问题。注释掉这些问题后，一切就都正常了。
我认为你不需要这些，因为\centering停止的影响超出了figure环境范围。
\documentclass[11pt]{article}
\usepackage{graphicx, epstopdf}
\usepackage[font=small,labelfont=bf,textfont=bf]{caption}
\usepackage{subcaption}
\usepackage{color}
\usepackage{url}
\usepackage{mathtools}
\usepackage{multirow}
\usepackage{cancel}
\usepackage{abstract}
\usepackage{csquotes}
\addtolength{\textwidth}{1in}
\addtolength{\textheight}{1in}
\addtolength{\evensidemargin}{0.5in}
\addtolength{\oddsidemargin}{-0.5in}
\addtolength{\topmargin}{-0.5in}
\usepackage{tocloft}
\usepackage[nottoc,notlot,notlof]{tocbibind}
\renewcommand{\cftsecleader}{\cftdotfill{\cftdotsep}}
\setcounter{secnumdepth}{0}
\newcommand{\HRule}{\rule{\linewidth}{0.35mm}}
\begin{document}
% this points to a separate .tex file for your title
% note: title.tex is formatted to include a blank page for double-sided printing
\input{./title.tex}
% this points to a separate .tex file for your abstract
% note: abstract.tex is formatted to include a blank page for double-sided printing
\input{./abstract.tex}
\tableofcontents
\listoffigures
\listoftables
\pagenumbering{arabic}
\thispagestyle{empty}
\clearpage
\section{Introduction and Theory}
This experiment is expected to demonstrate what role pulse shaping plays in the nuclear detection process. The objective of this experiment was to become familiar with assembling a basic nuclear pulse processing system. As part of this process we needed to observe and describe the different pulses created at each step of the system. It was also necessary to measure pulse shape parameters, explain why each step in the system is necessary, and describe the effect of the system component settings on the pulse shape.
\bigbreak
The need for pulse shaping in nuclear detection is explored. Pulse shaping refers to a series of operations that are performed on a raw pulse from a detector that make it easier to extract the desired information. The raw pulse (or anode pulse) that is created by the detector and Photo-Multiplier Tube (PMT) carries information about the charge collected and the time it took to collect that charge. It is generally easier to work with amplitudes of pulses rather than the areas under them so this anode pulse is passed through a preamplifier (preamp) which integrates the pulse. Then the height of the preamp pulse (which is now given in voltage) is proportional to the energy (charge collected) and the charge collection time is determined by the rise time of this pulse. The rise time of a preamp pulse is very fast in a charge sensitive (fast) preamp so it is necessary to take the derivative of this pulse to obtain a pulse with a wider rise time. An amplifier does this derivation which leads to a signal that has a better shape to determine the timing of the pulse while preserving the energy (charge) information. After these steps the pulse can be used by a multichannel analyzer (MCA) to determine an energy spectrum or by a single channel analyzer (SCA) which turns the pulse into a logic pulse for counting purposes.
\section{Procedure and Methods}
A pulse processing system was assembled according to the block diagram in Figure \ref{fig:sysblock}.
\begin{figure}[h]
\centering
\includegraphics[width=\textwidth]{example-image-a}
\caption{Block Diagram of System Setup}
\label{fig:sysblock}
% \flushleft
\end{figure}
\hspace{-30pt} A list of the equipment used is provided below.
\bigskip
\begin{enumerate}
\item Cs-137 source
\item 2-inch-diameter by 2-inch-long sodium iodide scintillator (2x2 NaI) coupled to a 2-inch-diameter 20-stage PMT
\item 14-pin PMT base with integrated preamp
\item nuclear instrument module (NIM) bin
\item high voltage (HV) power supply
\item amplifier
\item SCA
\item counter/timer
\item MCA
\item oscilloscope (scope)
\end{enumerate}
\bigskip
The final setup is shown in Figure \ref{fig:sysrealrot}. The experiment was carried out by connecting the scope to each component and viewing the pulse that was output at each step. The pulses viewed were from the anode of the PMT, preamp, amp (both unipolar and bipolar), and the SCA. The 10\%-90\% rise and 90\%-10\% fall times for these pulses were visually determined from the scope output as well as measured by the scope. The effects of amplifier gain and shaping time-constant, as well as voltage input to the PMT on the pulse shapes were determined. The setting for the components at each of these steps are detailed below. The counting rate was also determined by the counter/timer and three different pulse height spectra (PHS) were obtained with the MCA.
\begin{figure}[h]
\centering
\includegraphics[width=\textwidth]{example-image-a}
\caption{Photograph of Pulse Processing System Setup}
\label{fig:sysrealrot}
% \flushleft
\end{figure}
When initially setting up the system the source was put near the detector so the count rate was under $5,000 \frac{counts}{s}$. The HV power supply was set to $700 V$, the amplifier gain was set to $20$, the shaping time was set to $30 \mu s$, The SCA lower level division (LLD) was set to $0.2 V$ and the upper level division (ULD) was set to $10V$. The high voltage was adjusted to $600 V$ so the pulses coming from the amplifier had a peak value around $5 V$. The scope was autoset so we could see the pulses coming from the system.
The initial settings are unchanged in the following descriptions unless otherwise noted. When viewing the anode pulses the oscilloscope was initially set with a horizontal scale of $1 \mu s$ per division and a vertical scale of $50 mV$ per division. When viewing the preamp pulses the oscilloscope was initially set with a horizontal scale of $50 \mu s$ per division and a vertical scale of $100 mV$ per division. When viewing the amplifier unipolar pulses the oscilloscope was initially set with a horizontal scale of $5 \mu s$ per division and a vertical scale of $2 mV$ per division. The gain was then increased to 50 and decreased to 10 to observe the changes to the pulse due to amplifier gain. The shaping time was increased to $10 \mu s$ and decreased to $1 \mu s$ to observe the changes in the pulse due to shaping time. When viewing the amplifier bipolar pulses the oscilloscope was initially set with a horizontal scale of $5 \mu s$ per division and a vertical scale of $2 mV$ per division. When viewing the SCA pulses the LLD was initially set to $5 V$. Then the LLD was changed to $0.2 V$ and the ULD was set to $5 V$ to observe how this changed the pulses. To measure the counting rate the signal from the source was measured 10 times for $10 s$ and 10 more times for $40 s$. The source was then removed and the same counts were measured for the background. The background was then subtracted from the source to obtain an average pulse rate. The inital run of the MCA was done with the inital settings of for the experiment. The second spectrum was obtained with the amplifier gain set to 10. The third spectrum was obtained with the amplifier gain set to 20 and the HV supply set to $570 V$.
\bigskip
\section{Results and Discussion}
\bigskip
See the lab report guide for recommendations for your results and discussion section(s).
There are many ways to write and reference equations. One way is shown in Equation~\ref{eq:power}.
\begin{equation}
P = I V = I^2 R
\label{eq:power}
\end{equation}
And another way is shown in Equation~\ref{eq:multi}.
\begin{eqnarray}
P & = & I V \nonumber \\
& = & I^2 R
\label{eq:multi}
\end{eqnarray}
\subsection{Results}
\bigskip
The subsection is how you can break up a section. Note that the sections are listed in the table of contents and the subsections have a slightly different format (regular text, slightly indented).
\begin{figure}[h]
\centering
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{example-image-a}
\caption{Dish 1}
\label{fig:dish1}
\end{subfigure}
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{example-image-b}
\caption{Dish 2}
\label{fig:dish2}
\end{subfigure}
\begin{subfigure}{1.0in}
\includegraphics[width=\textwidth]{example-image-c}
\caption{Dish 3}
\label{fig:dish3}
\end{subfigure}
% \flushleft
\caption{Multi-figure figure}{This is an example of placing multiple figures together. You can reference sub-figures just like a single figure. As an example, Figure~\ref{fig:dish2} is a reference to the middle figure.}
\label{fig:multi_biscuits}
\end{figure}
\subsection{Discussion}
Placeholder for discussion subsection with an example of a citation. \cite{refMattingly}
\section{Conclusions}
See the lab report for recommendations for your conclusions.
% there are many ways to do references; this is a simple way if you only have a couple
\bibliographystyle{plain}
\begin{thebibliography}{9}
\bibitem{refMattingly}
John Mattingly and Dean J. Mitchell,
\enquote{A framework for the solution of inverse radiation transport problems,}
\emph{Trans. Nucl. Sci}, {\bf 75}(6), November 2010, pp. 3734-3743.
\end{thebibliography}
\end{document}
顺便提一句：我已将图形名称更改为example-images（因为我没有图形文件）。
附加建议
还会问：是否需要多个s （特别是在或\bigskip之前/之后？\section{...}\subsection{...}\begin{enumerate}
我认为这些是内置在类文件中的。你可以看看如果没有这些，你的文档看起来会不会更糟！
这就是我们更喜欢 LaTeX 而不是任何所见即所得的应用程序（如 Microsoft Word，您需要指定每个间距和格式……而这些已经在 LaTeX 类文件中完成了）的一个重要原因！