Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigation of $\alpha$ clustering with knockout reactions   Our goal is to reveal how the $\alpha$ cluster amplitude is probed through
$\alpha$ knockout reactions depending on reaction conditions, e.g., the
incident energy. We consider $^{20}$Ne($p$,$p\alpha$)$^{16}$O and
$^{120}$Sn($p$,$p\alpha$)$^{116}$Cd at 100-400 MeV within the distorted wave
impulse approximation (DWIA) framework. We introduce a masking function which
shows how the reaction amplitude in the nuclear interior is suppressed and
defines the probed region of the $\alpha$ cluster wave function. It is clearly
shown by means of the masking function that the $\alpha$ knockout reaction
probes the $\alpha$ cluster amplitude in the nuclear surface region, which is
the direct measure of well-developed $\alpha$ cluster states. A simplified form
of the masking function is introduced and the incident energy dependence of the
masking effect is investigated. $\alpha$ knockout reaction can probe the
$\alpha$ cluster amplitude in the nuclear surface region by choosing proper
kinematics owing to the masking effect originated from absorptions of
distorting potentials, and is a suitable method to investigate how $\alpha$
cluster states are spatially developed.

13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex