Activity at Dubna

Two kinds of aerogel samples radiators produced in Novosibirsk (Russia, Budker Institute of Nuclear Physics and Boreskov Institute of Catalysis)) and in Japan (Matsushita Company) were studied for the PHENIX High pt Upgrades Project. The absorption length for these two samples of aerogel was measured using methodic preposed in [1] is shown in Fig.43. The comparison of this two aerogel have been done in the test RUNs in KEK (December 2001 and May 2002). The results can be summarize as following:

• similar value of p.e. have been obtained when non-UV PMT was used;
• Novosibirsk aerogel sample provides 20 % larger value of p.e. than that of Matsushita aerogel sample with UV PMT (Quartz window).

図 43: The dependence of the absorption length ( $\lambda _{abs})$ from light wave length ( $\lambda _{\gamma })$) [2] for the aerogel samples produced in Novosibirsk (solid squares) and by Matsushita Company (solid circles).

It should be noted that Novosibirsk aerogel is hydrophilic (because of this their transparency degradate with time) instead of Matsushita aerogel and approximately three times expensive. These two facts requires to make decision against using Novosibirsk aerogel in this project.

In the May 2002 test RUN the comparison of Russian PMs (FEU-183 and FEU-143) and HAMAMATSU PM6233 have been performed. It was shown the most sensitive one of studied Russian PM FEU-183 have two times less sensitivity than HAMAMATSU PM6233. One of the possible option to be studied is a PM FEU-184Ti [5]. The comparison of sensitivities FEU-184Ti and HAMAMATSU PM6233 sensitivities is going to be performed in the end of 2002 in Dubna.

The possibility to make test measurement with aerogel counters was studied in July RUN in Dubna. The B4 (see. [6]) cannel was used for detection secondary particle. The count rate for $\pi$ with momentum $2 \pm 2\% GeV/c$ was at about 30 $\pi$ per burst (1 burst per 10 second) on the counters 2x2 ${\rm cm^2}$. The position dependence studies have been performed and gave the same results as in the May KEK test RUN.

Using this channel Dubna group is going at the end of this year to perform test measurement with the prototype of detector cells (Belle type, Integration Cube type). Dubna group also plans to take part in mechanical and engineering design and test detectors using Dubna accelerator.