IR Optimization, DID and anti-DID Page: 2 of 5
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
While the normal polarity of DID allows to compensate
locally the effect of crossing the solenoid field for the
incoming beam, the anti-DID (reversed polarity) allows to
effectively zero the crossing angle for the outgoing beam
(and pairs) - the U shaped distortion of the field lines is
adjusted to guide the low energy pairs to the extraction
aperture as shown in Fig.4.
used real solenoid field maps, and the shape of anti-DID
field used for GLD and LDC was specifically optimized
for these larger detectors with TPC (see below). We used
ILC final focus optics with different L* (distance between
IP and first quadrupole of FD): L*=3.51m for SiD and
L*=4.51m for GLD and LDC. The Final Doublet was
properly overlapped with the solenoid field.
Pairs at z= 3.51m
Figure 4: Field lines in LDC detector with anti-DID. The
anti-DID field shape has flattened central region, to ease
TPC calibration. The total crossing angle is 14mrad.
SiD with anti-DID, 14mrad, L*=3.51m
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
anti-DID max field (T)
Figure 5: Fraction of pairs directed into extraction
aperture in SiD versus anti-DID maximum field.
Figs.5-7 give quantitative results of tracking of
beamstrahlung pairs in realistic solenoid field of SiD
detector taking into account the anti-DID field. The shape
of anti-DID field was obtained earlier, in simulations with
2D and 3D magnetic models . The pairs were obtained
from beam-beam simulations by Guinea-Pig program .
Fig.5 shows the fraction of pairs entering the extraction
aperture versus maximum field of anti-DID. Fig.6 and
Fig.7 corresponds to the optimal strength of anti-DID and
show distribution of pairs 3.5m from the IP and
trajectories of the pairs along the SiD detector. One can
see that more than 60% of the pairs can be directed into
the extraction aperture.
Similar optimization, as for SiD, can be done for other
two detectors, GLD and LDC. In this optimization, we
Into incoming aperture : 41 /10000
Figure 6: Distribution of pairs at 3.5m from IP in SiD
detector when anti-DID is adjusted to direct pairs to the
extraction hole. The incoming and outgoing apertures are
shown by magenta and green colors.
- - - - r - '
1 - 2 3 - '
Figure 7: Trajectories of pairs in SiD with anti-DID.
Bt,Gs 01p, r Aasr, nm L, % Pex, %
SiD 205 -102 0.32 99.8 63
GLD 236 -96 0.65 >99 51
LDC 235 -122 1.01 98 49
LDC 354 -138 1.67 95 62
Table 1: Maximum field of anti-DID Bt, angle of the
incoming beam at the IP 01p, SR beam size growth A6s. (to
be added to ayo=5nm in quadratures), luminosity L taking
into account SR effects, fraction of pairs Pex directed to
extraction aperture. Total crossing angle is 14mrad.
The results of these optimizations are summarized in
the Table 1 in terms of the optimal field of anti-DID,
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Seryi, Andrei; Maruyama, Takashi; /SLAC; Parker, Brett & /Brookhaven. IR Optimization, DID and anti-DID, article, February 3, 2006; [Menlo Park, California]. (digital.library.unt.edu/ark:/67531/metadc878368/m1/2/: accessed January 21, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.