Minute of the CDC Group Meeting held on 24-May-01 (10:25-12:45 at Fuji-F2)
Japanese version is here
- Date and Place
May 24(Thursday), 2001 at KEK-Tsukuba (Fuji-2F)
- Attendants
M.Kobayashi, N.Khalatyan, K.Fujii, O.Nitoh, H.Kuroiwa, K.Hoshina, H.Hashiguchi, M.Araya, Y.Ichizaki, S.Kumano, R.Kuboshima
- Contents
- 1)Cosmic-ray measurement(H.Kuroiwa)
- a) He looked closely at the events which provide densely
populated small signals in the region close to the sense wires
in the plot of signal charge vs. drift distance shown
in the previous meeting.
He found two types of problematic events:
- i ) events with only very small electric noises somehow
synchronized to the triggers;
- ii) events with a track poorly reconstructed using hit points
associated with minor (secondary, tertiary....) peaks in the
sense wire signals.
The peak hunting part of the analysis program is sophisticated
enough to deal with double or multi-track events while
the track finding part is not yet refined enough correspondingly.
A "single shot discriminator" algorithm may work better for
cosmic ray tracks.
Therefore the excess of small signals can be removed simply by
ignoring hit points with small assigned charge, without any loss
of efficiency.
- b) He is now accumulating cosmic ray tracks using
the baby chamber with 20 ppm of oxygen. The spatial resolution
seems better than that obtained with 50 ppm of oxygen.
But he needs more statistics for 20 ppm data
in order to draw a conclusion.
- *) The reason why the events with only electric noises
are contained in the data is not understood.
- *) An improved algorithm for track finding
(pattern recognition) has to be applied
in a real multi-particle environment in which hit points
associated with "minor" peaks can not be ignored.
- *) Gas flow rate has to be increased to reduce
the oxygen content to a 20 ppm level because of limited
gas tightness of the baby chamber.
Where has the flammable gas detector once we had gone?
- *) He should estimate the life time of drift electrons
as a function of oxygen concentration from
the charge attenuation measured.
- *) Is the paper now in preparation going to include
the beam data results and/or the influence of
oxygen contamination?
Both should be included (Kobayashi's personal opinion).
- 2)Simulation program development based on Geant4(K.Hoshina)
For her talk on the development of the simulator program using Geant4
please take a look at
here ( CDCMeet20010524.ps.gz ) .
- 3)VME-based DAQ system(H.Hashiguchi)
He is now preparing a DAQ software using ROOT.
The performance of the software and the VME-based electronics is going
to be tested as soon as a prototype FADC module and a VME CPU Board
become available. The new DAQ system including the VME FADCs
will be ready for the experiment at the KEK PS scheduled in this fall.
- *) He and his colleagues have decided to use a VME CPU board
instead of a "VME crate controller" assuming a large amount of
data per event to be handled at a high trigger rate since
- i ) data transfer is much faster between a PC and a CPU board
than in the case of a PC and a "crate controller";
- ii) data selection and compression can be carried out within a
fast VME system.
- 4)Reports on the present status(M.Kobayashi)
- a) A brief summary of the activities of the JLC CDC Group so far.
Now only the Japanese version is available.
See this file.(in Japanese, 1 page, PS)
- b) He calculated the most probable energy loss as a function of
p/mc using the empirical formula given by R.M.Sternheimer and
R.F.Peierls.
Agreement with our data seems satisfactory in the 1/beta**2 region
and poorer on the Fermi plateau.
See this file.(1 page, PS)
The calculated values may be too large in the relativistic rise
region as in the case of argon based gases.
However as for carbon dioxide the Monte-Carlo calculation
by J.H.Cobb and W.W.M.Allison is in good agreement
with that given by the formula used.
See this file.(1 page, PS)
It should be noted that our data points were obtained by applying
a truncated mean method, which should be replaced
with those given by Landau-distribution fitting.
Hayasaka-kun is expected to do this job.
- 5)What to do in this fiscal year
- a) Tension measurements of the wires of the 4.6 m chamber,
which is now six years old, and realistic calculations of
the expected wire sags due to electrostatic force especially
for the sense wires. Kato-san will be in charge of this.
- b) Study of the wire material to be used for the field wires
(by Kato-san?).
Aluminum or copper beryllium?
Another possible candidate is a gold-plated carbon fiber.
- c) Beam experiment
place: KEK PS (T1 beam line)
time: This fall (November?)
subject: A study of the influence of positive ions on the
performance of a jet-type chamber filled with a cool gas
(TENTATIVE).
- *) The proposal for the experiment will be prepared at TUAT.
- *) A short text describing the motive of the experiment and
the basic idea will be written by Kobayashi-san.
The Japanese version has already been
prepared.(in Japanese, 3 pages, PS)
- !) Any other proposals, ideas, suggestions
are welcome in order to make the beam time productive.
- 6)Others
- *) Themes of master theses of the students from Tsukuba University.
- Kumano-kun: Study of the isochrones using the baby chamber
and the simulation by GARFIELD.
- Ichizaki-kun: Analysis of the beam data taken
with the Baby chamber.
- Kuboshima-san: Development of the simulator using Geant4?
- *) The next CDC meeting will be held on June 21st (Thu)
from 10:00 at the Room 425 in the Building No.3.
Go Buck to JLC CDC Subgroup Homepage