# Question on ADS geometry

**URL:** <https://openmc.discourse.group/t/question-on-ads-geometry/853>\
**Category:** User Support\
**Created:** [November 8, 2020, 3:36pm UTC](https://openmc.discourse.group/t/question-on-ads-geometry/853 "2020-11-08T15:36:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Pattarapol](https://avatars.discourse-cdn.com/v4/letter/p/5daacb/32.png) [@Pattarapol](https://openmc.discourse.group/u/Pattarapol)\
**Post date:** [November 8, 2020, 3:36pm UTC](https://openmc.discourse.group/t/question-on-ads-geometry/853/1 "2020-11-08T15:36:39Z")

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Dear OpenMC expert,  
I want to create a hexagonal geometry with the cylinder target at the center, but I don’t know how to add the cylinder target. Is there any example related to my problem?

 ![41365_2018_487_Fig4_HTML](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/9/986edc6eaf462bbf4b10f596ffe6596a2091c207.png)

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**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\
**Post date:** [November 11, 2020, 4:05am UTC](https://openmc.discourse.group/t/question-on-ads-geometry/853/2 "2020-11-11T04:05:13Z")

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When you fill the hexagonal lattice into a cell, the boundaries of that cell should account for the inner target region. I’ve put together a [quick example](https://nbviewer.jupyter.org/gist/paulromano/6012d8f5f4c61d743f8d17dbd1922a15) that demonstrates this.