Having a log per day

Currently my application is using log4net to log errors, the web.config for this is as followed:

<log4net> 
    <appender name="FileAppender" type="log4net.Appender.FileAppender">
        <file value="c:/paypal/logs/gateway.log" />
        <appendToFile value="true" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] – %message%newline" />
        </layout>
    </appender>
    <root>
        <level value="DEBUG" />
        <appender-ref ref="FileAppender" />
    </root>
</log4net>

However, the problem with this is that everyday the logs always go to gateway.log

Does anybody know a way to have a different log file per day using log4net?

Ideally I don't want to have to manually edit the web.config every night using a scheduled task.