Slides for the discussion Cosmic ray density

Cosmic ray density. Cosmic ray is  useful for the alignment between plates. Decay search Momentum measurement  not necessary for the location. Higher density  Fake (cosmic ray) interaction. Bern example.  Fake stop  Multi candidates in CS->ECC connection. Lower density  Momentum measurement accuracy?. Maximum measurable momentum.

ECC with black CS (current Nagoya strategy.)‏ 1.General scan the downstream plates(3~5). 2.search vertex candidates. 3.Scanback or Direct vertexing. Strong worry about the 2 nd, 3 rd, vertex by cosmic ray. --> no cosmic on the ECC with black CS. Next talker, Takahashi. ECC downstream

Momentum of mu from tau decay. Momentum measurement Strongest interest on the muon from tau decay. Most of them are below 5GeV. Or 10GeV.

Momentum measurement by angular method No need fine alignment Cell 1/2

dx Position resolution is sqrt(6)*  (x)‏ Momentum measurement by coordinate method Fine alignment is needed. Cell 3/2

Position resolution by current cosmic ray exposure. SUTS data by 24h cosmic exposure 1cm^2  0.9 micron for X  0.75 micron for Y  (momentum cut by angular method.) dx  (dx) = sqrt(3/2)*  (x)‏

1cm x 1cm x 12plates 226 tracks in scanning area (nseg>=5 theta<0.5)‏ dx  (dx) = sqrt(3/2)*  (x)‏

1.4cm x 1.4cm x 11plates 369 tracks in scanning area dx  (dx) = sqrt(3/2)*  (x)‏  From the point of alignment. Higher cosmic density doesn't give higher resolution. 1/3~1/5 of current exposure is enough to get same alignment accuracy(1micron).

Bigger scanning area give a number of track. It is competition between emulsion XY distortion and the scanning power.

Alignment for long range (cell length >=3,5)‏ The accumulation of the alignment error is of the order of Cell 1/2 (in worst case). For example,  cell length = 3, sqrt(6)*1micron = 2.4micron.  Cell length = 5, sqrt(10)*1micron=3.2micron. On the other hand, the signal of the coordinate method is Cell 3/2, which is enough big. Cell 3/2

From the point of alignment.  Higher cosmic density doesn't give higher resolution.  1/3~1/5 of current exposure is enough to get same alignment accuracy(1micron).

Ntrack = 281 starting from first 2plate && nseg>=3

Angle resolution (including scattering.)‏ Rms = sqrt(rms(theta1)^2 + rms(theta2)^2)‏ rms(theta) = 1.2/sqrt(2) = 0.85mrad

dx  (dx) = sqrt(3/2)*  (x)‏ Including scattering. theta^rms cut = 5mrad for each cell.