• Executive summary
• Continuation and next meetings
• Cooling channel design
• Design Considerations
• Which Experiments
• Beam Specifications

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Executive summary

The main aims and priorities set during the discussion were as follows

• A 10% cooling section of the linear 88 MHZ cooling channel will be
  designed, build, and exposed to a muon beam
• It was decided to propose a SINGLE BEAM EXPERIMENT supplemented by
  high intensity radiation tests
• The experiment should begin taking data in 2004
• a letter of intent should be prepared in spring 2001.
  

priorities before then are:

• prepare more detailed drawings and general requirements of the cooling section to be tested
• finding a beam and location for the experiment
• designing the beam emmittance measurement method and devices.
  

Continuation and next meetings

It was decided that the next general meetings in Europe devoted to the muon cooling experiment would take place on

• 28 March at CERN,
• 25 April at CERN
• 9 May at CERN (Plenary muon week)

As for collabortion with the US, it was decided to propose a meeting with our american friends during the week-end of NUFACT01.

The attendance of the London meeting was good, in particular many CERN people attended.

Cooling channel design

AIM: the aim of the ionization cooling experiment was spelled out: we want to predict the performance of the neutrino factory to better than a factor 2. This can be achieved if a 10% cooling channel (i.e. reduces the transverse emmittance in one plane, e.g. epsilon x, by 10%) is tested with a precision of 1%. (nb it is in fact somewhat better than that, (1.+0.1+-0.01)**20 = 6.7+-1.3).

Design Considerations

In response to a question by S. Geer, the justification for the CERN 44/88 MHZ scheme is the desire to avoid the induction linacs. This forces us to begin with low frequency RF cavities for the phase rotation. In addition, the scheme is well adapted to the SPL repetition rate, which can be based on the frequency of 44 MHz.

A 10% cooling system should consist of two cooling sections, each section being made of 8 cavities of 90 cm longitudinal dimension. the total is about 16 meters long, before and after which instrumentation should be placed.

A drawing of the system including facilities was considered highly desirable.

The baseline experiment is a section of a straight cooling channel, and contains no longitudinal cooling. It was noted however that attractive schemes such as a ring cooler have not yet proven to work, even on paper. However, they contain straight sections similar in design to a straight cooling channel, so that experience gained in pursuing a straight section test could be build on should the final design be modified.

Which Experiments

the basic experiment is

" Design Build Instrument a section of the cooling channel, place it into a beam and show that it works as desired "

more specifically, a cooling channel is characterized by the asymptotic equilibrium emmittance, which can be determined by plotting the output emmittance as a function of the input emmittance. This requires that a phase space at least as large as the design one be available at the input.

The choice of basic experiments was:

1. a particle-by-particle experiment. This implies single particle experimentation (such as the scintillating fibers shown at the meeting) but, provided the resolution on each of { x, px, y, py, E and t} is at least a factor 10 better than the spread in these quantities at equilibrium emmittance, it should allow complete measurement of the 6D emmittance reduction as function of beam parameters such as timing, energy and transverse emmittance parameters.
2. a bunched beam experiment. The advantage here is that this reproduces more closely the reality of operation at the neutrino factory. The input and output beams have to be characterized and the beam time structure has to be matched to the RF. mplies a 6D emmittance measurement. Instrumentation measuring the 6 dimensions and their correlations is not easy.
3. a high intensity blast experiment. This would test the ingeneering issues related to high intensities and is very important. It was pointed out however that it is not necessary to expose a whole cooling section to such a burst and that test of a single cavity/absorber/solenoid assmbly would be necessary and sufficient.

In the discussion that followed, and from the presentations during the workshop, it was decided to go for a SINGLE PARTICLE EXPERIMENT, complemented by BLAST tests. The information contained in a single particle experiment would allow detailed understanding of the device, while a bunched beam experiment would make this very dificult.

Beam Specifications

The decision to go for a single particle experiment leads to a revision of the previous assumption to locate oneself in TT1, where slow extraction is not an option. A priority was to find out the maximum duty cycle (or useful muons) one could get in TT1/TT7 beam lines.

More adequate beam lines for the purpose seem located at either the CERN East Hall or in laboratories with CW beams: PSI, RAL, TRIUMF. In particular a more detailed investigation of the EAST Hall and PSI beam lines and facilities was requested.

The goal is to have a letter of intent written in spring 2001. Details of the device to be tested (a good drawing, size, power consumption and floor space required etc..) are urgently needed, as well as of the measuring technique and devices.