Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determination of hydrogen cluster velocities and comparison with
  numerical calculations   The use of powerful hydrogen cluster jet targets in storage ring experiments
led to the need of precise data on the mean cluster velocity as function of the
stagnation temperature and pressure for the determination of the volume density
of the target beams. For this purpose a large data set of hydrogen cluster
velocity distributions and mean velocities was measured at a high density
hydrogen cluster jet target using a trumpet shaped nozzle. The measurements
have been performed at pressures above and below the critical pressure and for
a broad range of temperatures relevant for target operation, e.g., at storage
ring experiments. The used experimental method is described which allows for
the velocity measurement of single clusters using a time-of-flight technique.
Since this method is rather time-consuming and these measurements are typically
interfering negatively with storage ring experiments, a method for a precise
calculation of these mean velocities was needed. For this, the determined mean
cluster velocities are compared with model calculations based on an isentropic
one-dimensional van der Waals gas. Based on the obtained data and the presented
numerical calculations, a new method has been developed which allows to predict
the mean cluster velocities with an accuracy of about 5%. For this two cut-off
parameters defining positions inside the nozzle are introduced, which can be
determined for a given nozzle by only two velocity measurements.

29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph