A polarized proton beam incident on a Beryllium target was used for inclusive $\Lambda$(1116 meV) production at beam momenta of 13.3 GeV and 18.5 GeV. The beam polarization was transverse to the beam direction with magnitude 0.63(0.40) at 13.3(18.5)GeV. The trigger condition favoured forward produced $\Lambda$'s with moderately high p$\sb{\rm T}$(p$\sb{\rm T}\sim$ 1GeV). The $\Lambda$ polarization was measured and found to be in agreement with results from earlier experiments which used unpolarized proton beams. Analyzing power (A) and depolarization (D$\sb{\rm NN}$) of the $\Lambda$'s were both measured and compared with a hyperon polarization model in which the polarization arises from a Thomas precession effect. There is good agreement with its predictions: A = 0 and D$\sb{\rm NN}$ = 0. In particular, our measurement of D$\sb{\rm NN}$ = $-$0.009 $\pm$ 0.015 supports the idea that the valence quarks carry all of the hadron spin, since this assumption is implicit in the model's use of SU(6) wave functions to form final state hadrons from beam fragments and sea quarks.
The analyzing power of K$\sb{\rm s}$ was also measured at 13.3(18.5)GeV and found to be $-$0.094 $\pm$ 0.012($-$0.076 $\pm$ 0.015). We use the same model to predict A of K$\sb{\rm s}$, taking into account K$\sb{\rm s}$productgion from various sources (K$\sp\circ$, K$\sp\circ$ and K*) and find good agreement with the data.
Finally a small sample of $\bar\Lambda$ was isolated from the 18.5GeV sample and was found to have A = 0.03 $\pm$ 0.1, consistent with the model's prediction of zero.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/16193 |
| Date | January 1988 |
| Creators | Tonse, Shaheen Razak |
| Contributors | Miettinen, Hannu E. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 101 p., application/pdf |
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