PANDA Phase One Liu, Z.; Liu, B.; Shen, X. ...
The European physical journal. A, Hadrons and nuclei,
06/2021, Letnik:
57, Številka:
6
Journal Article
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Odprti dostop
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future ...antiProton ANnihilations at DArmstadt (PANDA or
P
¯
ANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton–nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model,
e.g.
through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the
Phase One
setup. The physics programme that is achievable during Phase One is outlined in this paper.
We report on the construction of a light pulser monitoring system for the electromagnetic lead tungstate (PbWO4) calorimeter of the future P¯ANDA experiment at FAIR. The system consists of a high ...intensity LED source, an optical fibre distribution system, and a novel and compact continuous light attenuation mechanism based on LCDs allowing operation inside the magnetic field of the P¯ANDA detector. The physics objectives of the P¯ANDA experiment require a highly sophisticated electromagnetic calorimeter covering an energy range spanning more than three orders of magnitude. In order to perform precision measurements with this electromagnetic calorimeter based on lead tungstate crystals in the high-luminosity environment of the P¯ANDA experiment, a frequent monitoring of radiation induced transmittance losses in the crystals on a level of 0.5% is required. This precision can be achieved on a day-by-day basis between regular π0/η invariant mass calibrations, performed at least once a day.
The exclusive charmonium production process in p¯p annihilation with an associated π0 meson p¯p→J/ψπ0 is studied in the framework of QCD collinear factorization. The feasibility of measuring this ...reaction through the J/ψ→e+e− decay channel with the AntiProton ANnihilation at DArmstadt (P¯ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the p¯p→π+π−π0 and p¯p→J/ψπ0π0 reactions are performed with PandaRoot, the simulation and analysis software framework of the P¯ANDA experiment. It is shown that the measurement can be done at P¯ANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.
.
This paper summarises a comprehensive Monte Carlo simulation study for precision resonance energy scan measurements. Apart from the proof of principle for natural width and line shape measurements ...of very narrow resonances with PANDA, the achievable sensitivities are quantified for the concrete example of the charmonium-like
X
(3872) state discussed to be exotic, and for a larger parameter space of various assumed signal cross-sections, input widths and luminosity combinations. PANDA is the only experiment that will be able to perform precision resonance energy scans of such narrow states with quantum numbers of spin and parities that differ from
J
P
C
=
1
-
-
.
The (P) over bar ANDA (anti-Proton ANnihiliation at DArmstadt) experiment will be one of the four flagship experiments at the new international accelerator complex FAIR (Facility for Antiproton and ...Ion Research) in Darmstadt, Germany. (P) over bar ANDA will address fundamental questions of hadron physics and quantum chromodynamics using high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c and a design luminosity of up to 2 x 10(32) cm(-2) S-1. Excellent particle identification (PID) is crucial to the success of the (P) over bar ANDA physics program. Hadronic PID in the barrel region of the target spectrometer will be performed by a fast and compact Cherenkov counter using the detection of internally reflected Cherenkov light (DIRC) technology. It is designed to cover the polar angle range from 22 degrees to 140 degrees and will provide at least 3 standard deviations (s.d.) pi/K separation up to 3.5 GeV/c, matching the expected upper limit of the final state kaon momentum distribution from simulation. This documents describes the technical design and the expected performance of the (P) over bar ANDA Barrel DIRC detector. The design is based on the successful BaBar DIRC with several key improvements. The performance and system cost were optimized in detailed detector simulations and validated with full system prototypes using particle beams at GSI and CERN. The final design meets or exceeds the PID goal of clean pi/K separation with at least 3 s.d. over the entire phase space of charged kaons in the Barrel DIRC.
The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N * and Delta spectroscopy. ...Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N * and Delta spectra. The future antiproton experiment (P) over bar ANDA will provide direct access to final states containing a (Xi) over bar Xi pair, for which production cross sections up to mu b are expected in (p) over barp reactions. With a luminosity of L = 10(31) cm(-2) s(-1) in the first phase of the experiment, the expected cross sections correspond to a production rate of similar to 10(6) events/day. With a nearly 4 pi detector acceptance, (P) over bar ANDA will thus be a hyperon factory. In this study, reactions of the type (p) over barp -> (Xi) over bar (+)Xi*(-) as well as (p) over barp -> (Xi) over bar*(+)Xi(-) with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
Abstract
The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of ...hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels:
$${\bar{p}}p \rightarrow {\bar{\varLambda }}\varLambda $$
p
¯
p
→
Λ
¯
Λ
and
$${\bar{p}}p \rightarrow {\bar{\varXi }}^+\varXi ^-$$
p
¯
p
→
Ξ
¯
+
Ξ
-
. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
Abstract
The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards
$$N^*$$
N
∗
and
$$\varDelta $$
...Δ
spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the
$$N^*$$
N
∗
and
$$\varDelta $$
Δ
spectra. The future antiproton experiment
$$\overline{\text{ P }}$$
P
¯
ANDA will provide direct access to final states containing a
$${\overline{\varXi }}\varXi $$
Ξ
¯
Ξ
pair, for which production cross sections up to
$$\mu \text{ b }$$
μ
b
are expected in
$$\bar{\text{ p }}$$
p
¯
p reactions. With a luminosity of
$$L=10^{31}$$
L
=
10
31
cm
$$^{-2}$$
-
2
s
$$^{-1}$$
-
1
in the first phase of the experiment, the expected cross sections correspond to a production rate of
$$\sim 10^6\, \text{ events }/\text{day }$$
∼
10
6
events
/
day
. With a nearly
$$4\pi $$
4
π
detector acceptance,
$$\overline{\text{ P }}$$
P
¯
ANDA will thus be a hyperon factory. In this study, reactions of the type
$$\bar{\text{ p }}$$
p
¯
p
$$\rightarrow $$
→
$${\overline{\varXi }}^{+}$$
Ξ
¯
+
$$\varXi ^{*-}$$
Ξ
∗
-
as well as
$$\bar{\text{ p }}$$
p
¯
p
$$\rightarrow $$
→
$${\overline{\varXi }}^{*+}$$
Ξ
¯
∗
+
$$\varXi ^{-}$$
Ξ
-
with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
Abstract
This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors,
$$|G_{E}|$$
|
G
E
|
and
$$|G_{M}|$$
|
G
M
|
, ...using the
$$\bar{p} p \rightarrow \mu ^{+} \mu ^{-}$$
p
¯
p
→
μ
+
μ
-
reaction at
$$\overline{\text {P}}\text {ANDA}$$
P
¯
ANDA
(FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at
$$\overline{\text {P}}\text {ANDA}$$
P
¯
ANDA
, using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is
$$\bar{p} p \rightarrow \pi ^{+} \pi ^{-}$$
p
¯
p
→
π
+
π
-
, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented.
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