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 共查询到20条相似文献,搜索用时 15 毫秒
1.
We calculateJ/ψ hadroproduction and emphasize the importance of theJ/ψ signal as a measure ofb \(\bar b\) production via the decayB→ψX and of the gluon structure function at lowx via χ hadroproduction followed by χ→ψγ decay. We compare with UA1 data and data at ISR energies and make predictions for ψ production at TEVATRON energies.  相似文献   

2.
NMR at 900 MHz     
An important factor in the development of solution state NMR has always been th e ability to produce stable and homogeneous magnetic fields. As higher and higher field strengths are reached the pressure is growing on manufacturers to produce NMR systems with greatly improved spectral resolution and signal to noise ratio. The introduction of the Varian 900 MHz INOVA system in August 2000 featuring Oxford Instruments 21.1 T magnet represents the latest pioneering development in NMR technology.  相似文献   

3.
M. Buscher 《中国物理 C》2010,34(9):1263-1268
Selected results from experiments at COSY-Jülich are presented: an attempt to measure the mass of the η meson with high precision (ANKE facility),first steps towards the detection of rare η decays (WASA),and several measurements of KK-pair production (ANKE,COSY-11,MOMO).  相似文献   

4.
Hydrophobic interactions have been studied before in detail based on hydrophobic polymers, such as polystyrene(PS). Because fluorinated materials have relatively low surface energy, they often show both oleophobicity and hydrophobicity at the macroscopic level. However, it remains unknown how fluorination of hydrophobic polymer influences hydrophobicity at the microscopic level. We synthesized PS and fluorine-substituted PS(FPS) by employing the reversible addition-fragmentation chain transfer p...  相似文献   

5.
Hans Strö  her 《中国物理 C》2009,33(12):1102-1104
The paper gives a brief introduction into the COSY-facility, the currently used detector systems (ANKE, TOF and WASA) and the targets (cluster jet, pellet and ABS), and it presents some recent results, which were obtained in the field of baryon excited states.  相似文献   

6.
With the construction of the new Radioactive Ion Beam Line in Lanzhou (RIBLL Ⅱ) which connecting the CSRm and the CSRe, an experimental setup.The Time-of-Flight (ToF) technique was recognized as one of the best ways for neutron detection and it, is employed by the neutrons wall. Considering the high neutron multiplicity, the detector shouldal so have the ability to resolve the multiple hits. Moreover, a high detection efficiency for the neutrons with energies ranging from 100MeV to 1 GeV is also required besides the high granularity. In this case, the sampling hadronic calorimeter type of detector has been selected. In order to estimate the performance of the detector and  相似文献   

7.
8.
We present a brief remark and introduction to event generators for tau-charm physics currently used at BESⅢ,including KKMC,BesEvtGen,Bhlumi,Bhwide,Babayaga and inclusive Monte-Carlo event generators.This paper provides basic information on event generators for BESⅢ users.  相似文献   

9.
We estimate ψψ production at collider energies in the framework of perturbative QCD. TheO s 2 )?(α s 4 ) parton cross-sections, with the non-relativistic approximation for the heavy quark bound states, are used. This first insight into the characteristics of the kinematical distributions allows predictions on the predominance of the quark, gluon orB meson production mechanisms in particular kinematical regions.  相似文献   

10.
Single-Photon Detection at Telecom Wavelengths   总被引:1,自引:0,他引:1       下载免费PDF全文
A single-photon detector based on an InGaAs avalanche photodiode has been developed for use at telecom wavelengths. A suitable delay and sampling gate modulation circuit are used to prevent positive and negative transient pulses from influencing the detection of true photon induced avalanches. A monostable trigger circuit eliminates the influence of avalanche peak jitter, and a dead time modulation feedback control circuit decreases the afterpulsing. From performance tests we lind that at the optimum operation point, the quantum efficiency is 12% and the dark count rate 1.5 × 10^-6 ns^-1, with a detection rate of 500 kHz.  相似文献   

11.
12.
Trigger efficiencies at BESⅢ were determined for both the J/ψ and ψ' data taking of 2009. Both dedicated runs and physics datasets are used; efficiencies are presented for Bhabha-scattering events, generic hadronic decay events involving charged tracks, dimuon events and ψ'→π+π-J/ψ, J/ψ→ 1+1- events.The efficiencies are found to lie well above 99% for all relevant physics cases, thus fulfilling the BESⅢ design specifications.  相似文献   

13.
Trigger efficiencies at BESⅢ were determined for both the J/ψ and ψ' data taking of 2009. Both dedicated runs and physics datasets are used; efficiencies are presented for Bhabha-scattering events, generic hadronic decay events involving charged tracks, dimuon events and ψ'→π+π-J/ψ, J/ψ→ 1+1- events.The efficiencies are found to lie well above 99% for all relevant physics cases, thus fulfilling the BESⅢ design specifications.  相似文献   

14.
Event generators at BESⅢ   总被引:1,自引:0,他引:1  
平荣刚 《中国物理 C》2008,32(8):599-602
We present a brief remark and introduction to event generators for tau-charm physics currently used at BESⅢ, including KKMC, BesEvtGen, Bhlumi, Bhwide, Babayaga and inclusive Monte-Carlo event generators. This paper provides basic information on event generators for BESⅢ users.  相似文献   

15.
The photoproduction of K+ mesons from the nucleon provides important constraints on the nucleon excitation spectrum and at threshold energies challenges effective field theories based on chiral perturbation in the strange quark sector. Preliminary cross-section measurements for γ(P, K+)A are presented at an unprecedented beam energy resolution. The data was collected at the MAMI-C facility in Mainz using the Crystal Ball Detector. A new method of K+ detection was used in which the K+ is tagged from its weak decay products in the detector crystals. This technique has application with other calorimeters at present and future hadron facilities.  相似文献   

16.
A power formula for erenkov radiation at finite temperature is derived in the framework of the generalized finite-temperature Cutkosky rules. Spins 1/2 and 0 are considered.  相似文献   

17.
Based on 9.0×106 J/ψ data collected at BES, a systematic physics analysis has been Performed. We confirmed the existence of ξ(2230) in J/ψ→γKK and observed for the first time the non-strange decay modes ξ(2230)→π+π0π0,and pp. The resonance and polarization parameters of f0(980) and f2(1270) were measured. The moment stUdy on J/ψ→γK+K revealed that the controversial fJ,(1710) is composed of two states, a 0++ and a 2++. With the help of PWA method, the spin-Parities for η(1440) and f0(1500) were obtained, and their main decay modes were found.  相似文献   

18.
19.
KAIUM at DAΦNE?     
The possibility of producing and detecting at DAΦNE a new hydrogen isotope formed by a (K ?+? e ???) bound system (Kaium) is addressed, considering a dedicated, and relatively simple experiment of short duration. If Kaium will be detected, it could in perspective pave the way for a series of highly sophisticated experiments focused on the precision measurement of several observables, as the K ?+????K ??? mass difference, strictly related to CPT invariance.  相似文献   

20.
The transverse energy and the charged-particle multiplicity at midrapidity are evaluated in a single-freeze-out model for different centrality bins at RHIC at = 130 and 200GeV. The predictions of the model are done at the freeze-out parameters determined earlier from measured particle yields and pT spectra. The results agree qualitatively well with the experimental data.  相似文献   

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