1. 2nd DEPFET workshop 3-6 May 2009
Pitch Options z d r
Same pitch in groups of 4 (one switcher channel)
z<0: zm+4 = zm/(1 + 4 d/r)
z>0: zm+4 = zm + zm 4 d/r
Unless: pitch > pitch_min
Adjust pitch_min to cover full acceptance with N pixel
N: number of pixel in a full ladder (also in layer 2!)
N/2: number of pixes in a half ladder (readout unit)
N/8: number of switcher channels in a half ladder r
(cm)
1.8
2.2 Z-
(mm) 34
40.5 Z+ 64
76.5 L 98
117
2nd DEPFET workshop 3-6 May 2009

2. 2nd DEPFET workshop 3-6 May 2009
Pitch Options N
1000
800
R (cm)
1.8
2.2
Pitch (const) (µm) 98
117
122
146
Max – (µm) 93
103
136
Max + (µm)
176
172
Min (µm) 88 N
2000
1600
R (cm)
1.8
2.2
Pitch (const) (µm) 49
58.5 61 73
Max – (µm) 93 76
Max + (µm)
176
172
Min (µm) 22 33 38 51
2nd DEPFET workshop 3-6 May 2009

3. 2nd DEPFET workshop 3-6 May 2009
Variable Pitch
P=103µm
Z=0, pixel
P=88µm
P=33µm
Z=0, pixel
P=22µm
2nd DEPFET workshop 3-6 May 2009

4. 2nd DEPFET workshop 3-6 May 2009
News from KEK
1) In the nano beam scheme, the final focusing magnets may come closer to the IP.
(This is not very likely now. We are planning to put the magnets even further from the IP, though not fixed yet. We still have some chance that we loose our theta acceptance for some other reasons.) We will study the impact of the acceptance change on physics analyses as follows:
Theta to be checked: (17, 20, 30) for the forward, (160, 150, 140) for the backward,
Mode: mathematical calculation (Ushiroda), B to tau nu (K. Hara), flavour tag (Sumisawa), tau to mu gamma (Inami), plus some charm analysis (tba) Thanks to helps from H.Ozaki and K.Trabelsi (fsim+trackerr), Miao He(IHEP) has started a study for the different acceptance cases with B -> J/psi Ks, pi+ pi, D+ D- physics modes.
The first results will be shown.
2) 1) will be coupled with a possible change in the beam energy asymmetry.
Since the machine design is always easier in the symmetric energy design, to achieve sophisticated nano beam collision, we may need to relax the asymmetry.
We will check both 3.5x8 and 4x7.
3) In the nano beam option, we first thought the final focusing magnets will be placed closer to the IP, and we worried that the magnetic field near the IP will be more complicated than present. We don't know if that is the case, but we will first check the impact of non-uniform magnetic field on the tracking anyway.
Seeing the result, we will discuss what we can/should do.
(Software coordinators + Tracking group will work on this task)
4) Change in the beam background
SR will be smaller in the nano beam option because the beam size at QCx will be much smaller. This will be confirmed by U-Tokyo group.
Final Q magnets closer to the IP will increase radiative Bhabha and spent electron background that come into the detector. If not closer, this will not be a big issue.
Toushek background could increase drastically. We must check how large it is.
For SVD2, I heard this simulation took 2 'young' Karim years.
I hope someone volunteers for doing this study.
Please send smart hard-working people in your institute for this urgent issue.
5) Beam Pipe radius
We have some chance to reduce the BP radius in the nano beam since the SR background won't be too severe. (maybe too optimistic) In any case, we are always willing to have smaller radius BP. We should know the impact of the first sensor position on some important physics modes. Some studies have been done, but nothing was put in the study report. We will revise the study or do new studies.
Xiang Ma (IHEP) tries to check the impact parameter resultions with a smaller raidus beam pipe by using trackerr. Now she can change the each layers' position and material thickness. Then the improvement/degradation caused by layer position/ material/intrinsic resolution are being checked.
Best regards,
Yutaka Ushiroda
2nd DEPFET workshop 3-6 May 2009