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Luminosity performance comparison: 5-6 Jun vs. 23 Dec 03

Luminosity performance comparison: 5-6 Jun vs. 23 Dec 03. Compare beam-current dependence of (specific) luminosity spot sizes Data sets 5-6 Jun: stable running , after a few rounds of optimization LEB: restored to 3 May config + new tune spot

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Luminosity performance comparison: 5-6 Jun vs. 23 Dec 03

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  1. Luminosity performance comparison: 5-6 Jun vs. 23 Dec 03 • Compare beam-current dependence of • (specific) luminosity • spot sizes • Data sets • 5-6 Jun: stable running , after a few rounds of optimization • LEB: restored to 3 May config + new tune spot • HEB: restored to 3 May config + 20 (addt’l) % of beta*y knob + better tune • by-3 pattern, 934 bunches, coasting • CRR data file: PHYSICS3_DATA:[pep2.ip.witold.spr03]lumb_t_2_5Jun • 23 Dec: stable running, then MD pushing currents • by-2 pattern, 1319 bunches, LER trickle • CRR data file: PHYSICS3_DATA:[pep2.ip.witold.win04]lumb_t_1_23Dec

  2. Beam currents & Luminosity: 23 Dec 03 LER current (23 Dec) L (23 Dec) HER current (23 Dec) Lsp (23 Dec)

  3. Beam currents & Luminosity: 5 Jun 03 LER current (5 Jun) L (5 Jun) HER current (5 Jun) Lsp (5 Jun)

  4. Bunch currents & L/bunch: 5 Jun vs. 23 Dec LER vs. HER bunch currents (5 Jun) LER vs. HER bunch currents (23 Dec) L/bunch (5 Jun) L/bunch (23 Dec) -12 % -22 %

  5. Specific luminosity: 5 Jun vs. 23 Dec Lsp (5 Jun) Lsp (23 Dec) -20 -25 % Lsp (5 Jun) Lsp (23 Dec) -12 %

  6. LER beam sizes: 5 Jun vs. 23 Dec LER x-size (23 Dec) LER x-size (5 Jun) +6 % LER y-size (5 Jun) LER y-size (23 Dec)

  7. HER beam sizes: 5 Jun vs. 23 Dec HER x-size (5 Jun) HER x-size (23 Dec) +5-10 % HER y-size (5 Jun) HER y-size (23 Dec)

  8. Summary • Compared to the 5-6 June data set, the 23 Dec data set exhibits • in the LER • peak bunch current now ~ 10% lower • x- spot size* + 6% (at the same Ib-), with comparable HER-current dependence • y-spot size* comparable (at the same Ib-) • both x & y spot sizes increase with increasing HER current • in the HER • peak bunch current now ~ 20% lower • x- spot size* +5 - 10 %, increases with HER current (??) • y- spot size* comparable, decreases with HER current (trickle + beam-beam) • Luminosity • achieved a peak luminosity of 7.2 E33 by pushing currents (mainly HER) • luminosity curves show only moderate saturation: we need more current! • at the same bunch-current product, the L/bunch is ~ 12% smaller • the peak L/bunch is 22% lower because (i) • the Lsp is smaller, and • (ii) the peak bunch currents are lower (for both rings, but mainly in the HER) • because of the different running mode (coast vs. trickle) and diferent bunch-current regime, hard to tell which beam is ‘weaker’.

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