Table 2.

Summary of the main characteristics of the 2012 vdM scans performed at the ATLAS interaction point. The nominal tranverse beam size is computed using the nominal LHC emittance (${\mathit{ϵ}}_N=3.75\mathit{\mu }$m-radians). The actual transverse emittance and single-beam size are estimated by combining the convolved transverse widths measured in the first scan of each session with the nominal IP $\mathit{\beta }$-function. The values of the luminosity/bunch and of $\mathit{\mu }$ are given for zero beam separation during the first scan. The specific luminosity decreases by 6–17% over the duration of a given scan session

Scan labels	I–III	IV–IX	X–XV
Date	16 April 2012	19 July 2012	22, 24 November 2012
LHC fill number	2520	2855, 2856	3311, 3316
Total number of bunches per beam	48	48	39
Number of bunches colliding in ATLAS	35	35	29
Typical number of protons per bunch $n_{1,2}$	$0.6\times {10}^{11}$	$0.9\times {10}^{11}$	$0.9\times {10}^{11}$
Nominal $\mathit{\beta }$-function at the IP (${\mathit{\beta }}^{\star }$) (m)	0.6	11	11
Nominal transverse single-beam size ${\mathit{\sigma }}_{\mathrm{b}}^{\mathrm{nom}}$ ($\mathrm{\mu }$m)	23	98	98
Actual transverse emittance ${\mathit{ϵ}}_N$ ($\mathrm{\mu }$m-radians)	2.3	3.2	3.1
Actual transverse single-beam size ${\mathit{\sigma }}_{\mathrm{b}}$ ($\mathrm{\mu }$m)	18	91	89
Actual transverse luminous size ${\mathit{\sigma }}_{\mathcal{L}}$ ($\approx {\mathit{\sigma }}_{\mathrm{b}}/\sqrt{2}$) ($\mathrm{\mu }$m)	13	65	63
Nominal vertical half crossing-angle ($\mathit{\mu }$rad)	$\pm 145$	0	0
Typical luminosity/bunch ($\mathit{\mu }{\mathrm{b}}^{-1}{\mathrm{s}}^{-1}$)	0.8	0.09	0.09
Pile-up parameter $\mathit{\mu }$ (interactions/crossing)	5.2	0.6	0.6
Scan sequence	3 sets of centred $x+y$ scans (I–III)	4 sets of centred $x+y$ scans (IV–VI, VIII) plus 2 sets of $x+y$ off-axis scans (VII, IX)	4 sets of centred $x+y$ scans (X, XI, XIV, XV) plus 2 sets of $x+y$ off-axis scans (XII, XIII)
Total scan steps per plane	25	25 (sets IV–VII)	25
		17 (sets VIII–IX)
Maximum beam separation	$\pm 6{\mathit{\sigma }}_{\mathrm{b}}^{\mathrm{nom}}$	$\pm 6{\mathit{\sigma }}_{\mathrm{b}}^{\mathrm{nom}}$	$\pm 6{\mathit{\sigma }}_{\mathrm{b}}^{\mathrm{nom}}$
Scan duration per step (s)	20	30	30