## D3 and D4 - point 4 - MBRB/MBRS

### D3 - MBRS

Nominal (ie. layout db) Current (at 7 TeV) 5520 A
Nominal Field (at 7 TeV) 3.5 T

### D4 - MBRB

Nominal Current (at 7 TeV) 5520 A
Nominal Field (at 7 TeV) 3.5 T

Constants

sepARC = 0.194;
sepIR4 = 0.420;
Dsep4 = 71.901;

lengthMBRB = 9.45 m
lengthMBRS = 9.45 m

Required Angle

AIP4 = ArcTan[(sepIR4 - sepARC)/2/Dsep4]

R0 = 0.0; (not used - below for completeness)

Normalized strength

Required Field

B = kd3L4*7000/.2998 = 3.88309 T

Bdl = B x 9.45 = 36.6952 Tm

Required Current

Transfer Function D3 - MBRS = 0.005991848 Tm/A (from layout database values quoted above)
Transfer Function D4 - MBRB = 0.0059918 Tm/A

current D3 at 7 TeV = Bdl/0.005991848 = 6124.19 A
current D4 at 7 TeV = 6124.24 A

However, if we look at the measured D3 TF provided by Sandor see plot

From a quick look at the plot TF at around 6000A is 0.665 T/kA or 6.251 T.m/kA. This gives us around 5870 A for D3.

From actual measured data D3 TF is around 0.000662406 T/A at 5900 A. This gives us around 5862 A for D3. In agreement.

From actual measured data D4 TF is around 0.000632282 T/Aat 6000 A. This gives us around 6141 A for D4.

ML April 08