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) %
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* %, 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’.