The zero degree calorimeters for the ALICE experiment Puddu, G.; Arnaldi, R.; Chiavassa, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2007, Volume:
581, Issue:
1
Journal Article
Peer reviewed
The Zero Degree Calorimeters (ZDC) for the ALICE experiment will measure the energy of the spectator nucleons in heavy ion collisions at the CERN LHC, providing a direct measure of the centrality of ...the collisions. ZDC are spaghetti calorimeters, which detect the Cherenkov light produced by the shower particles in silica optical fibers embedded in a dense absorber. The main characteristics of the ZP and ZN detectors are described in this article. The calorimeters were tested at the CERN SPS using pion and electron beams with momenta ranging from 50 to
200
GeV
/
c
. Test beam results such as the calorimeter response, the energy resolution, the signal uniformity and the localizing capability are presented.
The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The ...unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π-→ϱ→μ+μ- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.
In crop plants, deficiency of an essential element may drastically reduce growth rate and yield. Research on the use of leaf spectral properties in the detection of crop mineral deficiency is needed. ...The objective of this study was to examine the effects of Fe, S, Mg, and Mn deficiency on reflectance (R), absorptance (A), and transmittance (T) spectra of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), corn (Zea mays L.), and sunflower (Helianthus annuus L.) leaves. Plants were grown in the greenhouse in nutrient solution. Chlorophyll (Chl), Fe, S, Mg, and Mn concentrations and spectral properties were determined on the youngest fully expanded leaf when deficiency symptoms were clearly manifested. In all species, mineral deficiency affected leaf concentration of the deficient element and also of other elements. Nutrient deficiency reduced Chl concentration and A, and increased R and T. Iron deficiency severely affected all species, and corn was the species most sensitive to all deficiencies. Reflectance, A, and T spectra of leaves were correlated with leaf Chl concentration. Our results suggested that all nutritional deficiencies reduce leaf Chl concentration, and subsequently this reduction increases leaf R and T, decreases leaf A, and shortens the red-edge position, defined as the inflection point that occurs in the rapid transition between red and near-infrared. Modifications in leaf spectral properties were not characteristic of nutrient deficiency, but were always observed in the same wavelengths
Durum wheat (
Triticum durum Desf.) is commonly grown in dryland conditions, where environmental stress during grain filling can limit productivity and increase the dependency on stored assimilate. ...We investigated current assimilation and remobilization of dry matter and nitrogen during grain filling in N fertilized and unfertilized durum wheat subjected to different levels of water deficit during grain filling. Two durum wheat varieties, Appio and Creso, were grown in open-air containers with three rates of nitrogen fertilizer (not applied, N0; normal amount, NN; high amount, NH) and four water regimes during grain filling (fully irrigated treatment, FI; low, LWS, moderate, MWS and high water stress, HWS) across 2 years. Grain yield and dry matter and N accumulation and remobilization were positively affected by N availability and negatively by water stress during grain filling. The reduction of grain yield by severe post-anthesis water stress amounted to 27 and 37% for N0 and NN, respectively, and was associated with a decrease in kernel weight. There was also a small negative effect on the number of kernels per spike. Conversely, the duration of grain filling was not modified either by water stress or by nitrogen treatments. Severe water stress also reduced dry matter accumulation and remobilization by 36 and 14% in N0 plants and by 48 and 25% in NH plants. Similarly, N accumulation and N remobilization was reduced by 43% and by 16% in N0 plants and by 51% and by 15% in NH plants. Conversely, low and moderate water stress did not substantially modify the patterns of dry matter and nitrogen deposition in grain. Although remobilization of dry matter and N was less affected by water stress than accumulation, it was not able to counterbalance the reduction of assimilation and consequently it was not able to stabilize grain yield under drought.
ALICE at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied ...from observations like the production of mesons with charm and beauty quarks. These signals have to be studied as a function of energy density, which is determined by the centrality of collisions. One of the physics observables that is closely related with the centrality of the collision is the number of spectator nucleons that can be measured by the Zero Degree Calorimeters (ZDC). Having a direct geometric interpretation allows to extract the impact parameter with minimal model assumptions. This paper describes the readout system of the ZDC. The ZDC readout consists of a VME system with a ZDC Readout Card, a VME Processor, Discriminators, a ZDC Trigger Card, scalers, QDCs and TDCs. The system was successfully tested during the 2009 ALICE data taking and is currently operational at the LHC.
φ production in In–In collisions at 158 A GeV Arnaldi, R.; Banicz, K.; Borer, K. ...
The European physical journal. C, Particles and fields,
11/2009, Volume:
64, Issue:
1
Journal Article
Peer reviewed
Open access
The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of
φ
→
μ
μ
meson production. Differential ...spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the
p
T
spectra shows that the
φ
has a small radial flow, implying a weak coupling to the medium. The
T
eff
parameter measured in In–In collisions suggests that the high value observed in Pb–Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb–Pb collisions: though significantly smaller than measured by NA50 in the muon channel, it is found to exceed the NA49 and CERES data in the kaon channel at any centrality. The mass and width are found to be compatible with the PDG values at any centrality and at any
p
T
: no evidence for in-medium modifications is observed.
The electromagnetic form factors of the neutron in the time-like region have been measured for the first time, from the threshold up to
q
2 ⋟ 6
GeV
2
. The neutron magnetic form factor turns out to ...be larger than the proton one; the angular distribution suggests that for the neutron, at variance with the proton case, electric and magnetic form factors could be different. Further measurements are also reported, concerning the proton form factors and the
Σ
Σ
production, together with the multihadronic cross section and the
J/
Γ branching ratio into
n
n
.
The objective of the research was to quantify the changes in the accumulation of dry matter and N and P content of four durum wheat (
Triticum durum Desf.) varieties grown on two soil types ...(sandy-loam and clay-loam), differing for texture, nitrogen content and water holding capacity. Plants were grown in containers and were rainfed until anthesis; irrigation was performed during grain filling to avoid water stress. The difference in total vegetative weight and nitrogen and phosphorus content of plants between anthesis and maturity was used to indirectly estimate the relative contribution of pre-anthesis assimilation and remobilization to grain yield. The behaviour of the four varieties was similar as they ranked in the same order for pre-anthesis and post-anthesis dry matter accumulation and grain yield and differences in soil characteristics induced similar changes in dry matter, N and P accumulation and remobilization. Soil type greatly affected the patterns of dry matter, N and P accumulation and remobilization. Plants grown on clay-loam soil had higher dry weight and N and P content both at anthesis and at maturity and higher grain yield at maturity, compared to plants grown on sandy-loam soil and the remobilization of dry matter, N and P were 75, 140 and 55% higher. Most of the grain carbohydrates originated from photosynthates produced during grain fill, as the contribution of remobilization of dry matter to grain yield did not reach 30%, while most of the grain N and P originated from the remobilization of N and P accumulated prior to anthesis as remobilization of N accounted for 73–82% of grain N content and remobilization of P accounted for 56–63% of grain P content.
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