BNL-AGS E906实验：中性双超核观测的疑问
8 浏览量
更新于2024-09-05
收藏 1.16MB PDF 举报
"是否观察到中性双超核？"
这篇论文主要讨论了BNL-AGS E906实验，这是一个专注于双超核研究的重要实验，首次使用全电子方法产生了大量的双超核数据。在实验中，研究人员观察到了π-π-动量矩阵中的两个显著结构，分别位于（pπ-H，pπ-L）= (133,114) MeV / c和(114,104) MeV / c。最初，有人提出这两个结构可能源自3H + Λ4H对的形成，但作者指出，这个解释存在疑问。
文章中指出，通过$^9$ Be核捕获停止的Ξ-粒子产生单Λ超核，或高能Ξ-与目标中的$^9$ Be核相互作用，都不足以解释观察到的结构。因此，他们转向了Avraham Gal的假设，即衰变图像1可能与这些观测结构有关。在统计多碎片模型中，当考虑到图像1具有1%的两体π-分支比时，能够较好地描述E906实验的数据。
然而，作者还探讨了另一种可能性，即束缚的Λ3n原子核可能会在动量相关矩阵中产生明显结构，但这与E906实验的观测结果并不相符。因此，这一发现提出了关于双超核性质和衰变机制的新问题，需要进一步的研究来确定观察到的结构的确切来源。
关键词包括：超核、统计衰变模型、BNL-AGS E906实验。这篇论文的发表为理解双超核的性质提供了新的视角，并且对于超核物理学领域的发展具有重要意义。它不仅挑战了现有的解释，也为未来实验设计和理论研究指明了方向，旨在更深入地探索这些奇特的核子系统。
Physics Letters B 790 (2019) 502–508
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Has the neutral double hypernucleus
4
n been observed?
Sebastian Bleser
a
, Michael Bölting
a
, Theodoros Gaitanos
b
, Josef Pochodzalla
a,c,∗
,
Falk Schupp
a
, Marcell Steinen
a
a
Helmholtz Institute Mainz, Johannes Gutenberg University, 55099 Mainz, Germany
b
Aristotle University of Thessaloniki, 54124 Thessaloníki, Greece
c
Institute for Nuclear Physics, Johannes Gutenberg University, 55099 Mainz, Germany
a r t i c l e i n f o a b s t r a c t
Article history:
Received
16 November 2018
Received
in revised form 9 January 2019
Accepted
25 January 2019
Available
online 30 January 2019
Editor:
V. Metag
Keywords:
Hypernuclei
Statistical
decay model
The BNL-AGS E906 experiment was the first fully electronic experiment to produce and study double
hypernuclei with large statistics. Two dominant structures were observed in the correlated π
−
–π
−
momentum matrix at (p
π−H
, p
π−L
) = (133, 114) MeV/c and at (114, 104) MeV/c. In this work we argue
that the interpretation of the structure at (133, 114) MeV/c in terms of
3
H+
4
H pairs is questionable. We
show, that neither a scenario where these single- hypernuclei are produced after capture of a stopped
−
by a
9
Be nucleus nor interactions of energetic
−
with
9
Be nuclei in the target material can produce
a sufficient amount of such twin pairs. We have therefore explored the conjecture of Avraham Gal that
decays of the
4
nmay be responsible for the observed structure. Indeed, the inclusion of
4
nwith a
two-body π
−
branching ratio of 50% in a statistical multifragmentation model allows to describe the
E906 data remarkably well. On the other hand, a bound
3
n nucleus would cause a striking structure in
the momentum correlation matrix which is clearly inconsistent with the observation of E906.
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
Recently, a candidate for a weakly unbound resonant tetraneu-
tron
was observed in the missing-mass spectrum measured in the
double-charge-exchange reaction
4
He(
8
He,
8
Be) at the Radioactive
Isotope Beam Factory of RIKEN [1]. Prior to this experiment, first
positive indications of such a nucleus were found in 2002 at GANIL
employing the breakup of
14
Be nuclei [2]. In the hypernuclear
sector, the HypHI Collaboration investigated peripheral
6
Li+
12
C in-
teractions
at GSI and found intriguing enhancements in the d+π
−
and t+π
−
invariant mass. These enhancements were interpreted as
weak decays of neutral
3
n hypernuclei [3].
From
the theoretical point of view, the tetraneutron is rather
controversial. Several theoretical models exclude the existence of a
bound or narrow resonant tetraneutron [4–8]. On the other side,
calculations of Lashko and Filippov [9], Shirokov et al. [10,11]as
well as Gandolfi et al. [12] support a slightly unbound tetraneutron
with a resonance energy in agreement with the RIKEN measure-
ment.
In the case of the neutral
3
n hypernucleus, the theoretical
*
Corresponding author at: Helmholtz Institute Mainz, Johannes Gutenberg Uni-
versity,
55099 Mainz, Germany.
E-mail
address: pochodza@uni-mainz.de (J. Pochodzalla).
URL: https://www
.hi-mainz.de (J. Pochodzalla).
position is clear: based on our present understanding of strange
nuclei, this nucleus should not be bound [13–17].
In
view of this challenging situation – experimentally as well
as theoretically – it is surely justified to explore the possibility
of other bound or resonant neutral baryonic systems as well. Of
particular interest are nuclear systems with two hyperons. The
onset of binding in light double -hypernuclei has a consider-
able
impact on our understanding of three-body forces in dense
baryonic matter. For charged double hypernuclei, the theoretical
situation is unclear for the A = 4
4
H nucleus [18–21], but bind-
ing
is expected to definitely set in for A = 5 double hypernuclei
[22–24]. Unfortunately, there is no consensus about the stability
with respect to either the n [25–27] nucleus or the
4
nnu-
cleus
[17,28,29].
In
this work we reconsider data taken by the AGS-E906 exper-
iment
which searched for double hypernuclei via their sequential
pionic decay [30]. Studying different production scenarios, we find
hints for a bound
4
nsystem.
2. The E906 puzzle
In 2001, the AGS-E885/E906 collaboration announced the first
‘mass production’ of about 30
4
Hevents based on ∼10
4
stopped
−
[30]. The -hypernuclei are identified through the sequential
weak decay via π
−
emission after a (K
−
, K
+
) reaction deposited
https://doi.org/10.1016/j.physletb.2019.01.047
0370-2693/
© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.
下载后可阅读完整内容，剩余6页未读，立即下载
2021-08-19 上传
2021-08-24 上传
2021-12-07 上传
2021-08-09 上传
2021-09-12 上传
2021-09-10 上传
2022-11-03 上传
2024-11-08 上传
weixin_38545243
- 粉丝: 7
- 资源: 899
我的内容管理
展开
最新资源
- 构建基于Django和Stripe的SaaS应用教程
- Symfony2框架打造的RESTful问答系统icare-server
- 蓝桥杯Python试题解析与答案题库
- Go语言实现NWA到WAV文件格式转换工具
- 基于Django的医患管理系统应用
- Jenkins工作流插件开发指南：支持Workflow Python模块
- Java红酒网站项目源码解析与系统开源介绍
- Underworld Exporter资产定义文件详解
- Java版Crash Bandicoot资源库：逆向工程与源码分享
- Spring Boot Starter 自动IP计数功能实现指南
- 我的世界牛顿物理学模组深入解析
- STM32单片机工程创建详解与模板应用
- GDG堪萨斯城代码实验室：离子与火力基地示例应用
- Android Capstone项目：实现Potlatch服务器与OAuth2.0认证
- Cbit类：简化计算封装与异步任务处理
- Java8兼容的FullContact API Java客户端库介绍
