The use of High Purity Germanium detectors (HPGe) has been planned in some future experiments of hadronic physics. The crystals will be located close to large spectrometers where the magnetic ...fringing field will not be negligible and their performances might change. Moreover high precision is required in these experiments. The contribution of magnetic field presence and long term measurements is unique. In this paper the results of systematic measurements of the resolution, stability and efficiency of a crystal operating inside a magnetic field of 0.8
T, using radioactive sources in the energy range from 0.08 to 1.33
MeV, are reported. The measurements have been repeated during several months in order to test if any permanent damage occurred. The resolution at 1.117 and 1.332
MeV gamma-rays from a
60Co source has been measured at different magnetic fields in the range of 0–0.8
T and the results are compared with the previous data.
The response of a matrix of 25 lead tungstate (PWO) scintillator detectors, operated at -25 degrees C, to photons in the range 13 MeV-64 MeV has been measured at the tagged-photon facility at ...MAX-lab, Lund. The tapered PWO crystals, each with a length of 200 mm and a cross-section of 24.4 x 24.4 mm(2) in the front end, read out by 19 mm photomultiplier tubes, were arranged in a 5 x 5 matrix. The response was measured for photons directed towards the centre of the central crystal as well as for photons directed towards the corner of the central crystal, where four crystals meet. The obtained energy resolution surpasses what has been published so far and is close to the limit given by Poisson statistics and escaped energy. For photons directed towards the centre(corner) of the central crystal the relative energy resolution, defined as (FWHM/2.35)/E-gamma, decreases from 7.3%(11.0%) at E-gamma = 13 MeV to 3.3%(3.6%) at E-gamma = 64 MeV. The reconstructed point of impact of a photon in this energy range is determined with an uncertainty (one standard deviation) of 7.3 +/- 0.1 mm.
The reaction pd→He3η at threshold was used to provide a clean source of η mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay η→π+π−e+e− is measured to be ...(4.3±1.3±0.4)×10−4.
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.
An experimental study of nuclear reactions between Si-28 nuclei at 200 and 300 MeV/nucleon and hydrogen or deuterium target nuclei was performed at the CELSIUS storage ring in Uppsala, Sweden, to ...collect information about the reactions responsible for single-event effects in microelectronics. Inclusive data on Si-28 fragmentation, as well as data on correlations between recoils and spectator protons or alpha particles are compared to predictions from the Dubna cascade model and the Japan Atomic Energy Research Institute version of the quantum molecular dynamics model. The comparison shows satisfactory agreement for inclusive data except for He fragments where low-energy sub-barrier fragments and recoiling fragments with very large momenta are produced much more frequently than predicted. The yield of exclusive data are also severely underestimated by the models whereas the charge distributions of recoils in these correlations compare well. The observed enhancement in He emission, which may well be important for the description of single-event effects, is most likely to be attributed to alpha clustering in Si-28 nuclei.
Summary Background Calcipotriol and betamethasone dipropionate are both widely used, effective treatments for psoriasis. Vitamin D analogues and topical corticosteroids have different mechanisms of ...action in the treatment of psoriasis. A new vehicle has been developed in order to contain both calcipotriol (50 µg g−1) and betamethasone dipropionate (0·5 mg g−1) in an ointment form. By using calcipotriol and a corticosteroid together, greater efficacy may be achieved than by using either compound alone.
Objectives The present study was conducted in order to compare the clinical efficacy and safety of the combined ointment formulation used once daily with the vehicle ointment used twice daily, calcipotriol ointment used twice daily and the combined formulation used twice daily in psoriasis vulgaris.
Methods This was an international, multicentre, prospective, randomized, double‐blind, vehicle‐controlled, parallel group, 4‐week study in patients with psoriasis vulgaris amenable to topical treatment. Patients were randomized to one of four treatment groups: combined formulation once daily, combined formulation twice daily, calcipotriol twice daily or vehicle twice daily. Efficacy and safety were assessed.
Results There was no statistically significant difference in the mean percentage change in the Psoriasis Area and Severity Index (PASI) from baseline to end of treatment between the two combined formulation groups, but the difference in PASI reduction was significantly higher in the combined formulation groups (68·6% once daily, 73·8% twice daily) than in both the twice daily calcipotriol group (58·8%) and the vehicle group (26·6%). Safety data showed the frequency of adverse events to be less in the combined formulation groups than in both the calcipotriol group and the vehicle group. The proportion of patients with lesional/perilesional adverse reactions was less in the combined formulation groups and vehicle group than in the calcipotriol group (9·9% combined formulation once daily, 10·6% combined formulation twice daily, 19·8% calcipotriol, 12·5% vehicle).
Conclusions No statistically significant nor clinically relevant difference in efficacy was seen between the combined formulation used once daily and twice daily. When compared to vehicle ointment or calcipotriol ointment alone, the combined formulation was shown to be clearly more efficacious.
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
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
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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