Update on HI beams study Magdalena Kowalska supervised by Elena Benedetto BE/ABP/HSC 16 September 2015

Steps from last meeting: Investigate of the maximum intensity that one can put to stay below emit_vertical = 6 mm mrad (> 1.6 e13 p+). Determine the aperture of the collimator to keep the losses below a certain level.

Intensity evolution while increasing the initial intensity from 1.6 to 2.0 e13 intensitylosses% upgraded WBS1.6e13p % H: mm1.7e13p % V: 22.4 mm1.8e13p % 5 ms in PSB1.9e13p % 1st test2.0e13p % intensitylosses% upgraded WBS1.6e13p % H: mm1.7e13p % V: 22.4 mm1.8e13p % 5 ms in PSB1.9e13p % 2nd test2.0e13p % intensitylosses% upgraded WBS1.6e13p % H: mm1.7e13p % V: 22.4 mm1.8e13p % 5 ms in PSB1.9e13p % build in in flat file2.0e13p % intensitylosses% no WBS1.6e13p % 1.7e13p % 1.8e13p % 5 ms in PSB1.9e13p % 2.0e13p % intensitylosses% upgraded WBS1.6e13p % H: mm1.7e13p % V: 22.4 mm1.8e13p % 15 ms in PSB1.9e13p % 2.0e13p %

Intensity evolution while increasing the initial intensity from 1.6 to 2.0 e13

emit_xincrease in emit_xemit_yincrease in emit_ylosses% of the beam init2.16E E-06 WBS E %9.74E % % 1st test E %9.86E % % E %9.92E % % E %1.01E % % 5 ms22.11E %1.01E % % WBS E %9.74E % % 2nd test E %9.86E % % E %9.92E % % E %1.01E % % 5 ms22.11E %1.01E % % no WBS E %1.02E % % E %1.03E % % E %1.04E % % E %1.07E % % 5 ms22.12E %1.09E % % WBS built in E %9.74E % % E %9.86E % % E %9.93E % % E %1.01E % % 5 ms22.11E %1.01E % % WBS E %9.76E % % E %9.87E % % E %9.87E % % E %9.96E % % 15 ms22.13E %9.95E % %

Emittance evolution while increasing the initial intensity from 1.6 to 2.0 e13 !!! Strange behaviour of horizontal emittance when intensity exceeds 1.8e13p+ -> should we trust calculations?

Emittance evolution while increasing the initial intensity from 1.6 to 2.0 e13

Comments: Horizontal emittance blow up is always the highest for the 1.8e13p+ beam and it goes with the smallest amount of losses. Vertical emittance blow up scale with the intensity however it stays below a certain level due to the aperture restriction in vertical plane. For 15 ms, the increase is 2.25 % and 1.07 % in horizontal and vertical plane respectively, while keeping losses below 6%. The experiment was performed for the WBS with the dimensions +/ mm and +/ mm as it was agreed to be a reference point.

Steps from last meeting: Investigate of the maximum intensity that one can put to stay below emit_vertical = 6 mm mrad (> 1.6 e13 p+). Determine the aperture of the collimator to keep the losses below a certain level.

Aperture of the collimator aperturelosses% 38_vs_38ongoing 37_vs_ % 36_vs_ % 35_vs_ % 34_vs_ % 33_vs_ % 32_vs_ % 31_vs_ % *100_vs_38ongoing *100_vs_ % *100_vs_ % Model: square aperture Losses are not expected to occur in horizontal plane Study of the first 5ms Our loss budget: 5 – 6 % Injection beam loss estimated to be 2.25 % Left: 2.75 – 3.75 %

Contribution of the loss at the collimator to the total loss pattern

Loss pattern (aperture 37 mm vs 37 mm) Almost 60 % of the lost particles are collimated at the absorber. Almost 15 % of the lost particles ends in next 5 m of the lattice at BR.QFO82 or at BR.BHZ82.

Loss pattern (aperture 37 mm vs 37 mm)

Losses (x vs y)

Losses (x vs y), test case black body 31 mm

Losses (x vs y), test case carbon 31 mm

Comments: Horizontal emittance blow up is always the highest for the 1.8e13p+ beam and it goes with the smallest amount of losses. Vertical emittance blow up scale with the intensity however it stays below a certain level due to the aperture restriction in vertical plane. For 15 ms, the increase is 2.25 % and 1.07 % in horizontal and vertical plane respectively, while keeping losses below 6%. From the preliminary results, it looks like a rectangular carbon absorber with an aperture of 38 mm in both planes should keep the losses occurring during the chicane fall below 3%. Similar experiment should be performed for the new design of the WBS.

Simulations for carbon absorber with an aperture of 38 mm are ongoing… … However, they are some results for the absorber with an aperture of 37 mm (I expect to see similar behaviour for 38 mm)

Intensity evolution while increasing the initial intensity from 1.6 to 2.0 e13 “Similarity” to no WBS case -> do we really collimate the HI beam if the losses stay below 3% ?

emit_xincrease in emit_xemit_yincrease in emit_ylosses% of the beam init2.16E E-06 WBS E %9.74E % % 1st test E %9.86E % % E %9.92E % % E %1.01E % % 5 ms22.11E %1.01E % % no WBS E %1.02E % % E %1.03E % % E %1.04E % % E %1.07E % % 5 ms22.12E %1.09E % % new WBS E %9.92E % % H: 37 mm E %1.00E % % V: 37 mm E %1.01E % % E %1.04E % % 5 ms22.11E %1.06E % %

Emittance evolution while increasing the initial intensity from 1.6 to 2.0 e13 !!! Again something strange happens when the intensity goes beyond 1.8e13p+

Emittance evolution while increasing the initial intensity from 1.6 to 2.0 e13 !!! Big vertical emittance blow up. However for the intensity up to 1.8e13p+ it stays below % and seems to converge

Comments: Horizontal emittance blow up is always the highest for the 1.8e13p+ beam and it goes with the smallest amount of losses. Vertical emittance blow up scale with the intensity however it stays below a certain level due to the aperture restriction in vertical plane. For 15 ms, the increase is 2.25 % and 1.07 % in horizontal and vertical plane respectively, while keeping losses below 6%. From the preliminary results, it looks like a rectangular carbon absorber with an aperture of 38 mm in both planes should keep the losses occurring during the chicane fall below 3%. Similar experiment was performed for the new design of the WBS with an aperture of 37 mm.

Comments: Assuming similar behaviour for 38 mm of an aperture of WBS, one can conclude that: The intensity could go up to 1.8e13p+ if PSB can handle an increase of the normalized vertical emittance from 5.96 mm mrad to 6.17 mm mrad (3.56 %). Intensity of 1.6e13p+ will change the vertical emittance by (1.61 %). Study of longer life of the beam inside the machine are needed. Also, once agreed on approximate aperture, one could add the errors to the PSB lattice and see the effect of the perturbed orbit on emittance increase.

Appendix:

Beam evolution after the injection

1 st turn

2 nd turn

3 rd turn

4 th turn

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6 th turn

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15 th turn

Losses after the injection

1 st turn

2 nd turn

3 rd turn

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15 th turn