Shintake monitor meeting, 24 December 2008

Participants : Y.Kamiya, T.Yamanaka and M.Oroku ( Tokyo university ) J.Urakawa, N.Terunuma, S.Kuroda, T.Okugi, S.Araki (KEK)

1. Background exceeded the signals.

Q : How to estimate the S and N ? - normalization ?
A : RMS distribution in the histograms to separate S and N
Q : What is difference from the previous experiment using the LW setup last year?
A : the shower development of the background is different,
A : PMTs in the detector system have been calibrated with cosmic rays. S was estimated by intensities of lasers and beams
Q : Shower shape was observed with lower PMT-HVs ( gains ) ?
A : no in this time
Q : Did the detector properly worked during the experiments ? S/N must be correctly estimated during experiments.
Q : Understanding of background : where do they come ? front or back or up or down or right or left the beam condition must be controlled
A : Those experiments were not for the background study. large area for Pb shields; installation of a screen monitor for further studies ; measurement of OTR/ODR and laser beam at the same detector ( APD )
Q : screen - mm position information ; laser random reflection
A Okugi : measurement of laser beam and ODR from 45 degree knife edge by a APD ( LW group )
Q : Can you install all instruments in the vacuum pipe with limited number of ports?
screen, knife edge, etc.
A : position adjustment by a screen monitor ( mm order )
C : laser pulse width 8ns FWHM, so position information must be better in mm order
A : alignment target with pin holes ( 174, 30, 8, 2 degree modes ) instead of slit ; holes with 200um diameter
Q : You must prepare the performance, detailed procedures
Is it possible for multiple purposes ?, i.e. both for 2 and 8 degree modes
A : Is it possible to align the beam to 200um pin hole ?
C : it is difficult to tune beam in a hole.
We will prepare followings; Alignment of beam line in the detector ?
Q : aperture of collimator ?
A : 20mm diameter in the long collimator
Q : scan range in X ?
A : it is difficult to increase the range, but it can be 2.5mm by beam scan
C : not good to change the magnet currents
Q : Is it enough with +/- 4mm in total ?
A : First, we try the beam scan, probably to use the upstream magnets for wider scan in parallel as much as possible, i.e. 10mm ?
Q : angular acceptance of the collimator ?
A : tunable,
Q : Do we know the present beam trajectory ?
A :No ( precisely )
C : 20mm collimator would be enough w/o sextupoles since the initial alignment should be good ( < mm ).
Q: How to insure the beam position in the IP vacuum pipe ?
Q : Can you adjust laser beams for 10mm positions ?
A : It is possible to move the optics with +/- 10mm.
Q : Laser waist position ( +/- a few mm ) can be aligned ?
Q : Do we need vertical scan?
A : the laser focus must be changed
Q : Do you monitor the waist position ?
A : we can not.
Q : What plan will be in February -March ?
A : Master theses; final review on 20 January,
Q : IP-BSM signals can be available at the ATF control room for beam tuning ?
A : We will prepare such signals.
Q : The signals must be available for non-experts.
C : Somebody must accompany in beam tuning time.
A : We need strong support from the optics ( beam tuning) group for the moment.
Q : What is your plan by February?
A : Target - screen and folders were ordered by Yamanaka. ODR-target and the LW actuator will be borrowed from Stewart laser cubic target to KEK machine shop
A : We will borrow the spares . ( i.e. remote controllable actuator ) In this time, no ODR target, but only the actuator ports for screen/actuator, camera
C : Screen at IP and correct S/N estimation are important
Q : You need EPICS installation in your LINUX to communicate with the control system
just for data transformation for realtime monitor
the installation by Terunuma/ATF and new PC ( rack-mount )
A : no special software is used. VME driver, GPIB library
Q : Support of the detector will be ordered by ATF ( Terunuma ) Can you de-mount the detector?
A : We will do it in a week of 26th January.
Q : Send drawing of setup of detector.
C : background monitor is essential, which can be used for tuning, i.e. knob
A : Optics of 2 and 8 degree modes will be commissioned in February.
Q : Can we use it to measure the beam size ?
A : No. It takes more time.
C : You should explain clearly the availability of IP-BSM for beam tuning with beam size measurement.
Q : How long dose it take to commissioning the optics with 2 and 8 modes? , One month ?
A : position sensitive detector at downstream is missing at present.
Q : When will you get PSDs?
A : We can transport laser beams and get the interference. But, the laser position can not be measured w/o PSD.
A : It costs 400,000 yen/set (PSD and electronics) times 4 for 2, 8, 30, 174 degree modes
So, it is 1,600,000 yen in total. , where 2,8,30 with the same 2 PSDs-set. 174 with the second 2 PSDs-set.
Q : the appointed date of delivery
A : 2-3 weeks
C : buy 2sets.
Q : What the PSD is for?
A : To monitor the laser position for each mode. Those are also used when one change the crossing modes.
Q : 75nm beam size needs 30 degree mode ( 80nm - 400nm).
A : We can start the 30 deg. commissioning, first.
A : 2 and 8 degree modes can be compared with the carbon wire scanner.
Q : signal sensitivity with 2 and 8 degree compared to the laser wire scanner?
A : it is half.
Q : Are you available on 7th January ?
A : Yes
The same pulse width ( 8ns FWHM ) both in LW and interference .