Investigating the Electromagnetic Structure of the Nucleon and Light Nuclei at Jefferson Lab

在杰斐逊实验室研究核子和轻核的电磁结构

基本信息

批准号：
SAPIN-2015-00040
负责人：
Sarty, Adam
金额：
$ 3.2万
依托单位：
Saint Mary's University
依托单位国家：
加拿大
项目类别：
Subatomic Physics Envelope - Individual
财政年份：
2019
资助国家：
加拿大
起止时间：
2019-01-01 至 2020-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688761
关键词：
Investigating Electromagnetic Structure Nucleon Light

项目摘要

The primary objective of this research project is to continue collaborative efforts at the Thomas Jefferson National Accelerator Facility ("Jefferson Lab") in Newport News, Virginia, which are specifically aimed at probing the structure of the nucleon using a high energy electron beam. This work will be accomplished in collaboration with the Super BigBite Spectrometer (SBS) Collaboration in Hall A at Jefferson Lab. During this grant period, Jefferson Lab will be emerging from the past transition "upgrade period" phase - having upgraded the beam energy from 6 GeV to 12 GeV - and beginning to utilize equipment specifically designed and built for the higher energy. This proposal includes a plan to ensure continued scientific contributions and student training with the early-running Hall A experiments (experiments focusing not only on nucleon structure, but also on that of light nuclei - particularly the triton three-nucleon system), but with primary emphasis remaining on preparation/development projects associated with a series of specific later-running SBS experiments that will probe nucleon structure functions at very high momentum transfers. The driving physics goals of all aspects of this project are related to improving understanding of the transition from the 'strong (non-perturbative) QCD' regime of relatively large distance scales of approximately 1 to a few fermis (where hadronic degrees of freedom are most appropriate), to the 'perturbative QCD' regime of much shorter distance scales.******Sarty has been working with Jefferson Lab's Hall A Collaboration for two decades, and during the past few years of equipment development for the lab's upgrade, Sarty and his students contributed to design/testing projects for Hall A's SBS group of experiments. The SBS experiments are designed to probe nucleon structure at very high momentum transfer; the hallmark experiment of this group being E12-07-109 ("Large Acceptance Proton Form Factor Ratio Measurements at 13 and 15 GeV/c^2 using Recoil Polarization Method"). This SBS group of experiments requires the construction of new equipment - a spectrometer, calorimeters, detectors - which will be completed by the collaboration during this granting period. Sarty's group has taken a lead role in preparing one part of the SBS detection system: a scintillator-based Coordinate Detector (CDet) to provide required fast timing and accurate position for the scattered electron detection - critical aspects needed for the very high radiation background environment of the E12-07-109 experiment. The CDet will consist of 0.5mm tall (4cm thick) scintillator strips, stacked to form two planes roughly 3m x 1m in size, for a total of 2352 channels of readout; Sarty's group will continue its work to ensure the CDet is constructed and an appropriate data acquisition system is ready for use when it is needed for SBS nucleon structure experiments at the end of the granting period.

该研究项目的主要目标是继续在弗吉尼亚州纽波特纽斯的托马斯·杰斐逊国家加速器设施（“杰斐逊实验室”）进行合作，该设施专门致力于使用高能电子束探测核子的结构。这项工作将与位于杰斐逊实验室 A 厅的 Super BigBite 光谱仪 (SBS) 合作完成。在此资助期间，杰斐逊实验室将摆脱过去的过渡“升级期”阶段 - 将束流能量从 6 GeV 升级到 12 GeV - 并开始使用专门为更高能量设计和制造的设备。该提案包括一项计划，以确保通过早期运行的 A 厅实验（实验不仅关注核子结构，还关注轻核结构 - 特别是 Triton 三核子系统）继续做出科学贡献和学生培训，但主要包括重点仍然放在与一系列特定的后续运行的 SBS 实验相关的准备/开发项目上，这些实验将在非常高的动量转移下探测核子结构功能。该项目各个方面的驱动物理目标与提高对从大约 1 的相对较大距离尺度到几个费米（其中强子自由度最大）的“强（非微扰）QCD”体系的转变的理解有关。适当），到更短距离尺度的“微扰 QCD”体系。*******Sarty 已经与杰斐逊实验室的 Hall A 协作机构合作了二十年，在过去几年的设备开发过程中，在实验室升级期间，Sarty 和他的学生为 A 厅的 SBS 实验组的设计/测试项目做出了贡献。 SBS 实验旨在探测极高动量传递下的核子结构；该小组的标志性实验是 E12-07-109（“使用反冲偏振法在 13 和 15 GeV/c^2 处进行大接受质子形状因子比测量”）。 SBS 的这组实验需要建造新设备——光谱仪、量热仪、探测器——这些设备将在本授权期内通过合作完成。 Sarty 的团队在准备 SBS 探测系统的一部分方面发挥了主导作用：基于闪烁体的坐标探测器 (CDet)，为散射电子探测提供所需的快速定时和准确位置 - 这是极高辐射背景环境所需的关键方面E12-07-109 实验的结果。 CDet 将由 0.5 毫米高（4 厘米厚）的闪烁体条组成，堆叠形成两个尺寸约为 3 m x 1 m 的平面，总共 2352 个读出通道； Sarty 的小组将继续努力，确保 CDet 建成，并在授权期结束时 SBS 核子结构实验需要时准备好适当的数据采集系统。