Tuesday, 29 August 1995

                      M E M O R A N D U M                            


To:      A. Schopper / PPE (SPS co-ordinator)

From:    N. Doble, K. Elsener, L. Gatignon / SL-EA

Copies:  P. Grafstr|m / SL-EA,

Subject: Operational modes of beamlines from T4 during 1996
--------------------------------------------------------------------------------

The following information should be taken into account by users of the P0, H8
and H6 beams when submitting their beam requests for the proton periods of
1996 (ions are not considered here):


1) beamlines from T4 and intensity
   -------------------------------

The 450 GeV proton beam hitting T4 is serving three beamlines:
            P0 (mostly 450 GeV protons, sometimes secondary electrons)
            H8 (450 GeV protons, secondary beams)
            H6 (secondary beams).
All three beams are strongly linked - operation is therefore problematic and has
to be carefully optimised.
 
The intensity on T4, at least as long as the neutrino experiments are running, is
limited to about 1.5 to 2.0*1012 protons per burst. The T4 target head is usually
No. 1 (i.e. 300 mm Be) - other thicknesses can be chosen on request and in
agreement with the users of the P0, H8 and H6 beamlines. If a run at nominal
intensity is required for NA48 in P0, about 5*1012 protons on T4 are needed with
target head No. 3 (200 mm Be) - such conditions should be requested explicitly.
 
 
2) H8, H6 and P0 running
   ---------------------
 
For the most frequent mode of operation, P0 is operational (450 GeV protons),
allowing the following schemes for H8 and H6 (switching between these modes
should be kept to a minimum!):
 
 a) H8=-200 GeV (+tertiary beams) -->> H6 = -120 GeV (+tertiary)
 b) H8=-300 GeV      -->> H6 = -120 GeV (+tertiary)
 c) H8=+180 GeV (+tertiary beams) -->> H6 = +120 GeV (+tertiary)
 
Secondary beams can be either hadrons or electrons, separated by synchrotron
radiation. Tertiary electron or hadron beams are produced from an intermediate
target in the beamline.
 
Note that while H8 has no other possibilities (due to the lack of a horizontal
bending magnet at the beginning of the beamline), H6 can have other momenta
at different production angles - i.e. H6 is somewhat more flexible.
 
There are four special modes of operation:
 
  a) H8 microbeam (450 GeV protons) -->> H6=+205 GeV (+tertiary)
        (P0 off or P0 electrons)
 
  b) H8 low energy secondary beams (e.g. 20 GeV, 10 GeV):
        (H6 off - exceptions might be discussed if H8 is at low  momentum
               for a longer period of time).
 
  c) H6 low energy secondary beams (e.g. 20 GeV, 10 GeV):
        if this is not possible with a large production angle, then H8 has to
        be at low energy, too, or H8 off.
 
  d) P0 uses electron beams for calibration:
        H8 +450 GeV/c microbeam (H6 at +205 GeV/c plus tertiary)
     or H8 +180 GeV/c plus tertiary  (H6 at +120 GeV/c plus tertiary)
     or H8 at -200 GeV/c plus tertiary (H6 at -120 GeV/c plus tertiary)
     or H8 at -300 GeV/c or -400 GeV/c
        with H6 at -120 GeV/c or -200 GeV/c plus tertiary
 
  FOR THESE MODES, A REQUEST HAS TO BE EXPLICITLY MADE in the
  beam time request submitted by the users at the beginning of the year, i.e.
  before the years schedule is made.