Experimental searches for exotic multiquark particles

1989 ◽  
Vol 67 (12) ◽  
pp. 1148-1152
Author(s):  
H. -W. Siebert
Keyword(s):  
Proton Beam ◽  
Neutron Beam ◽  
High Intensity ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Inclusive Production ◽  
Missing Mass ◽  
Beam Experiment

Experimental searches for "exotic" multiquark hadrons are reported. In a hyperon beam experiment at the Organisation Européenne pour la Recherche Nucléaire-superproton synchrotron (CERN-SPS), evidence was found for narrow states at 3.1 GeV/c2, with charges + 1,0, and −1, decaying into Λ, [Formula: see text], and pions. Similar signals were also seen in a neutron beam experiment at Serpukhov. These states, called U (3100), are tentatively explained as [Formula: see text] systems, i.e., [Formula: see text]. Such states were proposed more than a decade ago. New hyperon beam experiments in preparation at CERN and Fermilab will study these states, provided they exist. The proposed multiquark systems H = uuddss and [Formula: see text] are also discussed. One candidate for the decay H(2175) → Σ−p was observed in a propane buble chamber exposed to a proton beam. At Brookhaven National Laboratory, a missing-mass experiment in a high-intensity K− beam will search for the H, and the new hyperon beam experiments will search for inclusive production of both H and P.

Search for new particles

1977 ◽  
Vol 355 (1683) ◽  
pp. 493-513
Keyword(s):  
Mass Spectrum ◽  
Proton Beam ◽  
High Intensity ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
New Type ◽  
New Particles

We present a description of an experiment carried out at the 30GeV Alternating Gradient Synchrotron of the Brookhaven National Laboratory. The experiment used a high intensity slow extracted proton beam of between 10 10 and 2 × 10 12 protons per pulse and measured the e + e - mass spectrum from the reaction p+Be→e + e - +X. The result of this experiment shows the production of a new type of particle, J, which decays to e + e - with a width consistent with zero. Experimental searches for more new particles will also be presented.

The e+–H experiment of the Bielefeld–Brookhaven collaboration

1996 ◽  
Vol 74 (7-8) ◽  
pp. 361-366 ◽  
Author(s):  
W. Raith ◽  
A. Hofmann ◽  
M. Weber ◽  
K. G. Lynn
Keyword(s):  
Cross Sections ◽  
High Intensity ◽  
National Laboratory ◽  
Positron Beam ◽  
Theoretical Work ◽  
Brookhaven National Laboratory ◽  
Experimental Results ◽  
Experimental Setup ◽  
Open Questions ◽  
Remaining Time

The Bielefeld–Brookhaven collaboration began in 1989 and was originally scheduled for a duration of three and then six years and has recently been extended for about one more year. It will end in 1996 for reasons of manpower and funding. The goal of this collaboration was to measure integral and differential e+–H cross sections by employing the high-intensity positron beam (HIP) of the Brookhaven National Laboratory, anticipated to provide an electrostatically guided beam of 109 moderated positrons s−1. This goal has not yet been reached. Over all these years, the HIP operation has been suffering from a variety of technical difficulties, despite the great efforts of all parties involved. Nevertheless, since the HIP situation is improving, we will continue this collaboration and try to reach the goal within the remaining time. Our experimental results obtained with low-current positron beams thus far are discussed together with related experimental and theoretical work of other groups. Particular attention is given to open questions. The present experimental setup at the Brookhaven National Laboratory is described in detail. The planned measurements are outlined in order of their priority.

Chemical and orientational imaging of polymeric samples

1994 ◽  
Vol 52 ◽  
pp. 68-69
Author(s):  
H. Ade ◽  
B. Hsiao ◽  
G. Mitchell ◽  
E. Rightor ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Ethylene Terephthalate ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Carbonyl Groups ◽  
Aromatic Rings ◽  
Edge Structure ◽  
X Ray ◽  
Scanning Transmission ◽  
Polymeric Samples ◽  
X Ray Absorption

We have used the Scanning Transmission X-ray Microscope at beamline X1A (X1-STXM) at Brookhaven National Laboratory (BNL) to acquire high resolution, chemical and orientation sensitive images of polymeric samples as well as point spectra from 0.1 μm areas. This sensitivity is achieved by exploiting the X-ray Absorption Near Edge Structure (XANES) of the carbon K edge. One of the most illustrative example of the chemical sensitivity achievable is provided by images of a polycarbonate/pol(ethylene terephthalate) (70/30 PC/PET) blend. Contrast reversal at high overall contrast is observed between images acquired at 285.36 and 285.69 eV (Fig. 1). Contrast in these images is achieved by exploring subtle differences between resonances associated with the π bonds (sp hybridization) of the aromatic groups of each polymer. PET has a split peak associated with these aromatic groups, due to the proximity of its carbonyl groups to its aromatic rings, whereas PC has only a single peak.

Sign in / Sign up

Export Citation Format

Share Document